You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@qpid.apache.org by "Eagy, Taylor" <te...@BlackbirdTech.com> on 2013/08/07 18:55:44 UTC
Python Connections Hang from Subprocesses
Hello,
I'm having an issue connecting multiple Python subprocesses to the qpid C++ broker. I have a main Python process that imports qpid.messaging at the top and spawns a few multiprocessing.Process objects that try to create a Qpid connection to the broker. Before I spawn the processes though, the main process creates a connection to the Qpid broker just fine, but all of the subprocess code hangs when it trys to connect to the qpid broker. I know qpid is supposed to be multi-threaded, but what about multiprocess with Python? What could be causing the connections to hang from the subprocesses? Is there some singleton object that isn't getting released that's blocking the other subprocesses from connecting?
Thanks,
TJ
Re: Python Connections Hang from Subprocesses
Posted by Bill Freeman <ke...@gmail.com>.
I've got no experience with multiprocessing.Process. My only thought at
the moment is to see if avoiding connecting to the broker in the parent
allows the child to run. Maybe Process has some shared lock in its socket
code (though that should have prevented BasicHTTPServer too)?
On Thu, Aug 8, 2013 at 9:42 AM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Like I said in the original post this is in a multiprocessing.Process()
> object which uses the subprocess module to create a subprocess and runs the
> run() function in that subprocess.
> You can see the documentation here:
> http://docs.python.org/2/library/multiprocessing.html#multiprocessing.Process
>
> I'm not using threads or the threading module. Thanks for the reminder
> about multiple sessions. I had forgotten about that. This means I will have
> to share the same Connection object between multiple processes. Does the
> Connection object serialize fine when transferring via the pipe?
>
> -----Original Message-----
> From: Bill Freeman [mailto:ke1g.nh@gmail.com]
> Sent: Wednesday, August 07, 2013 5:51 PM
> To: users
> Subject: Re: Python Connections Hang from Subprocesses
>
> By the way, I presume that you know that you can have multiple sessions on
> one connection?
>
>
> On Wed, Aug 7, 2013 at 5:49 PM, Bill Freeman <ke...@gmail.com> wrote:
>
> >
> >
> >
> > On Wed, Aug 7, 2013 at 5:35 PM, Eagy, Taylor <teagy@blackbirdtech.com
> >wrote:
> >
> >> What O/S are you running this on?
> >>
> >>
> >>
> >> Ubuntu 12.04 LTS
> >>
> >> What does the code that spawns the subprocess look like?
> >>
> >>
> >>
> >> So my Process objects have a run() method that is called as the
> >> subprocess.
> >>
> >
> > Ok. Unless I miss my guess, this is not a subprocess. This is a thread.
> > Your object is probably a subclass or threading.Thread, and you never
> > import subprocess anywhere. If you ran "ps -alxww" in another
> > terminal, there wouldn't be a line for more than one process.
> >
> >>
> >>
> >>
> >> import qpid.messaging # at the top of the Python module
> >>
> >>
> >>
> >> def run():
> >>
> >> // some other non-qpid setup
> >>
> >>
> >>
> >> conn = qpid.messaging.Connection(qpid_endpoint)
> >>
> >> conn.open() <-- hangs here
> >>
> >> self.sess = conn.session()
> >>
> >> I have done this when there was already a connection to the broker,
> >> but
> > that other connection was a qmf.console connection, which does not use
> > qpid.messaging under the hood.
> >
> > Someone else will have to speak to the thread safety of
> > qpid.messaging, because we have now exceeded my experience in that area.
> >
> >
> >>
> >> Can you, even when the subprocess is hung, run something like spout,
> >> drain, or qpid-config, e.g.;
> >>
> >> qpid-config queues
> >>
> >> from another console window on the same box?
> >>
> >>
> >>
> >> Yes, I can connect to the queue if I try to connect from another
> >> module (which runs a new copy of the Python interpreter).
> >>
> >> ________________________________
> >> From: Bill Freeman [ke1g.nh@gmail.com]
> >> Sent: Wednesday, August 07, 2013 4:21 PM
> >> To: users
> >> Subject: Re: Python Connections Hang from Subprocesses
> >>
> >> Just in case it makes me (or someone else) think of something else:
> >>
> >> What O/S are you running this on?
> >>
> >> What does the code that spawns the subprocess look like?
> >>
> >> Can you, even when the subprocess is hung, run something like
> >> spout, drain, or qpid-config, e.g.;
> >>
> >> qpid-config queues
> >>
> >> from another console window on the same box?
> >>
> >> Bill
> >>
> >>
> >> On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <teagy@blackbirdtech.com
> >> >wrote:
> >>
> >> > Oops. Let me clean it up a bit.
> >> >
> >> > def attach(self):
> >> >
> >> > """
> >> > Attach to the remote endpoint.
> >> > """
> >> > if not self._connected:
> >> > self._connected = True
> >> > self._driver.start()
> >> > self._wakeup()
> >> > self._ewait(lambda: self._transport_connected and not
> >> > self._unlinked())
> >> >
> >> > def _ewait(self, predicate, timeout=None):
> >> >
> >> >
> >> > result = self._wait(lambda: self.error or predicate(), timeout)
> >> > <--
> >> It
> >> > times out here.
> >> > self.check_error()
> >> > return result
> >> >
> >> >
> >> > ________________________________
> >> > From: Eagy, Taylor [teagy@BlackbirdTech.com]
> >> > Sent: Wednesday, August 07, 2013 2:50 PM
> >> > To: users@qpid.apache.org
> >> > Subject: RE: Python Connections Hang from Subprocesses
> >> >
> >> > Bill thanks for your response. The subprocess definitely runs when
> >> > I
> >> don't
> >> > try to connect to the broker. Running a HTTPServer in it works too.
> >> > It
> >> just
> >> > doesn't connect to the qpid broker. I did a little digging and I
> >> > believe this is where it is hanging:
> >> >
> >> > (In Connection class)
> >> >
> >> > 270 @synchronized
> >> >
> >> > 271 -<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints-pysrc.html#
> >> >
> >> > def attach<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints.Connection-class.html#attach
> >> > >(self):
> >> >
> >> > 272 """
> >> > 273 Attach to the remote endpoint.
> >> > 274 """
> >> > 275 if not self._connected:
> >> > 276 self._connected = True
> >> > 277 self._driver.start<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints-pysrc.html#
> >> > >()
> >> > 278 self._wakeup()
> >> > 279 self._ewait(lambda: self._transport_connected and not
> >> > self._unlinked())
> >> >
> >> > The parent Python process can connect successfully, but the
> >> > self._transport_connected never gets set to True for all of the new
> >> > Connection objects created in the subprocesses that are trying to
> >> connect
> >> > to the same broker. Where does this get set to True?
> >> > Could this have something to do with the predicate because it
> >> > doesn't return an error it just times out?
> >> >
> >> >
> >> > 212 -<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints-pysrc.html#
> >> >
> >> > def _ewait<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints.Connection-class.html#_ewait
> >> >(self,
> >> > predicate, timeout=None):
> >> >
> >> > 213 result = self._wait(lambda: self.error or predicate(),
> >> timeout<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints-pysrc.html#
> >> > >)
> >> > 214 self.check_error<
> >> >
> >> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
> >> id.messaging.endpoints-pysrc.html#
> >> > >()
> >> > 215 return result
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > Thanks,
> >> > Taylor
> >> > ________________________________
> >> > From: Bill Freeman [ke1g.nh@gmail.com]
> >> > Sent: Wednesday, August 07, 2013 2:00 PM
> >> > To: users
> >> > Subject: Re: Python Connections Hang from Subprocesses
> >> >
> >> > Subprocesses (using the subprocess module, or even the older exec
> >> stuff, as
> >> > opposed to threads, or even forked clones) are relatively trouble
> >> > free
> >> in
> >> > python (except maybe on Windows, whose process model has that
> >> > Microsoft difference). I've certainly made multiple connections to
> >> > a broker from
> >> one
> >> > python process, as well as using tools like spout and drain, which
> >> > are
> >> both
> >> > written in python, while my main development project is running
> >> connected.
> >> >
> >> > Maybe there are broker configuration items which can affect this.
> >> > If
> >> so, I
> >> > hope that someone knowledgeable will speak up. But I doubt that
> >> > this is the problem.
> >> >
> >> > Are you sure that your subprocess runs? It might be trying to
> >> > report an error to you. Of, if you have pipes configured for
> >> > interaction with the invoking processor, it might be waiting on one
> of those.
> >> >
> >> > You could, temporarily, instead of your intended code, have the
> >> subprocess
> >> > invoke something like BasicHTTPServer, and see if you can interact
> >> > with
> >> it
> >> > using your browser. If that also fails, it leaves the broker
> >> > connection out as the source of your problems.
> >> >
> >> > Possibly easier is to have it log its arrival at various points, so
> >> > you
> >> can
> >> > be sure where it is getting stuck. If you've already confirmed
> >> > that
> >> it's
> >> > in the broker connect, forgive me, and wait for a better answer.
> >> >
> >> > Bill
> >> >
> >> >
> >> > On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor
> >> > <teagy@blackbirdtech.com
> >> > >wrote:
> >> >
> >> > > Hello,
> >> > >
> >> > >
> >> > >
> >> > > I'm having an issue connecting multiple Python subprocesses to
> >> > > the
> >> qpid
> >> > > C++ broker. I have a main Python process that imports
> >> > > C++ qpid.messaging
> >> at
> >> > the
> >> > > top and spawns a few multiprocessing.Process objects that try to
> >> create a
> >> > > Qpid connection to the broker. Before I spawn the processes
> >> > > though,
> >> the
> >> > > main process creates a connection to the Qpid broker just fine,
> >> > > but
> >> all
> >> > of
> >> > > the subprocess code hangs when it trys to connect to the qpid
> broker.
> >> I
> >> > > know qpid is supposed to be multi-threaded, but what about
> >> multiprocess
> >> > > with Python? What could be causing the connections to hang from
> >> > > the subprocesses? Is there some singleton object that isn't
> >> > > getting
> >> released
> >> > > that's blocking the other subprocesses from connecting?
> >> > >
> >> > >
> >> > >
> >> > > Thanks,
> >> > >
> >> > > TJ
> >> > >
> >> >
> >>
> >
> >
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@qpid.apache.org
> For additional commands, e-mail: users-help@qpid.apache.org
>
>
RE: Python Connections Hang from Subprocesses
Posted by "Eagy, Taylor" <te...@BlackbirdTech.com>.
Like I said in the original post this is in a multiprocessing.Process() object which uses the subprocess module to create a subprocess and runs the run() function in that subprocess.
You can see the documentation here: http://docs.python.org/2/library/multiprocessing.html#multiprocessing.Process
I'm not using threads or the threading module. Thanks for the reminder about multiple sessions. I had forgotten about that. This means I will have to share the same Connection object between multiple processes. Does the Connection object serialize fine when transferring via the pipe?
-----Original Message-----
From: Bill Freeman [mailto:ke1g.nh@gmail.com]
Sent: Wednesday, August 07, 2013 5:51 PM
To: users
Subject: Re: Python Connections Hang from Subprocesses
By the way, I presume that you know that you can have multiple sessions on one connection?
On Wed, Aug 7, 2013 at 5:49 PM, Bill Freeman <ke...@gmail.com> wrote:
>
>
>
> On Wed, Aug 7, 2013 at 5:35 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
>
>> What O/S are you running this on?
>>
>>
>>
>> Ubuntu 12.04 LTS
>>
>> What does the code that spawns the subprocess look like?
>>
>>
>>
>> So my Process objects have a run() method that is called as the
>> subprocess.
>>
>
> Ok. Unless I miss my guess, this is not a subprocess. This is a thread.
> Your object is probably a subclass or threading.Thread, and you never
> import subprocess anywhere. If you ran "ps -alxww" in another
> terminal, there wouldn't be a line for more than one process.
>
>>
>>
>>
>> import qpid.messaging # at the top of the Python module
>>
>>
>>
>> def run():
>>
>> // some other non-qpid setup
>>
>>
>>
>> conn = qpid.messaging.Connection(qpid_endpoint)
>>
>> conn.open() <-- hangs here
>>
>> self.sess = conn.session()
>>
>> I have done this when there was already a connection to the broker,
>> but
> that other connection was a qmf.console connection, which does not use
> qpid.messaging under the hood.
>
> Someone else will have to speak to the thread safety of
> qpid.messaging, because we have now exceeded my experience in that area.
>
>
>>
>> Can you, even when the subprocess is hung, run something like spout,
>> drain, or qpid-config, e.g.;
>>
>> qpid-config queues
>>
>> from another console window on the same box?
>>
>>
>>
>> Yes, I can connect to the queue if I try to connect from another
>> module (which runs a new copy of the Python interpreter).
>>
>> ________________________________
>> From: Bill Freeman [ke1g.nh@gmail.com]
>> Sent: Wednesday, August 07, 2013 4:21 PM
>> To: users
>> Subject: Re: Python Connections Hang from Subprocesses
>>
>> Just in case it makes me (or someone else) think of something else:
>>
>> What O/S are you running this on?
>>
>> What does the code that spawns the subprocess look like?
>>
>> Can you, even when the subprocess is hung, run something like
>> spout, drain, or qpid-config, e.g.;
>>
>> qpid-config queues
>>
>> from another console window on the same box?
>>
>> Bill
>>
>>
>> On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <teagy@blackbirdtech.com
>> >wrote:
>>
>> > Oops. Let me clean it up a bit.
>> >
>> > def attach(self):
>> >
>> > """
>> > Attach to the remote endpoint.
>> > """
>> > if not self._connected:
>> > self._connected = True
>> > self._driver.start()
>> > self._wakeup()
>> > self._ewait(lambda: self._transport_connected and not
>> > self._unlinked())
>> >
>> > def _ewait(self, predicate, timeout=None):
>> >
>> >
>> > result = self._wait(lambda: self.error or predicate(), timeout)
>> > <--
>> It
>> > times out here.
>> > self.check_error()
>> > return result
>> >
>> >
>> > ________________________________
>> > From: Eagy, Taylor [teagy@BlackbirdTech.com]
>> > Sent: Wednesday, August 07, 2013 2:50 PM
>> > To: users@qpid.apache.org
>> > Subject: RE: Python Connections Hang from Subprocesses
>> >
>> > Bill thanks for your response. The subprocess definitely runs when
>> > I
>> don't
>> > try to connect to the broker. Running a HTTPServer in it works too.
>> > It
>> just
>> > doesn't connect to the qpid broker. I did a little digging and I
>> > believe this is where it is hanging:
>> >
>> > (In Connection class)
>> >
>> > 270 @synchronized
>> >
>> > 271 -<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints-pysrc.html#
>> >
>> > def attach<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints.Connection-class.html#attach
>> > >(self):
>> >
>> > 272 """
>> > 273 Attach to the remote endpoint.
>> > 274 """
>> > 275 if not self._connected:
>> > 276 self._connected = True
>> > 277 self._driver.start<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints-pysrc.html#
>> > >()
>> > 278 self._wakeup()
>> > 279 self._ewait(lambda: self._transport_connected and not
>> > self._unlinked())
>> >
>> > The parent Python process can connect successfully, but the
>> > self._transport_connected never gets set to True for all of the new
>> > Connection objects created in the subprocesses that are trying to
>> connect
>> > to the same broker. Where does this get set to True?
>> > Could this have something to do with the predicate because it
>> > doesn't return an error it just times out?
>> >
>> >
>> > 212 -<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints-pysrc.html#
>> >
>> > def _ewait<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints.Connection-class.html#_ewait
>> >(self,
>> > predicate, timeout=None):
>> >
>> > 213 result = self._wait(lambda: self.error or predicate(),
>> timeout<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints-pysrc.html#
>> > >)
>> > 214 self.check_error<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qp
>> id.messaging.endpoints-pysrc.html#
>> > >()
>> > 215 return result
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > Thanks,
>> > Taylor
>> > ________________________________
>> > From: Bill Freeman [ke1g.nh@gmail.com]
>> > Sent: Wednesday, August 07, 2013 2:00 PM
>> > To: users
>> > Subject: Re: Python Connections Hang from Subprocesses
>> >
>> > Subprocesses (using the subprocess module, or even the older exec
>> stuff, as
>> > opposed to threads, or even forked clones) are relatively trouble
>> > free
>> in
>> > python (except maybe on Windows, whose process model has that
>> > Microsoft difference). I've certainly made multiple connections to
>> > a broker from
>> one
>> > python process, as well as using tools like spout and drain, which
>> > are
>> both
>> > written in python, while my main development project is running
>> connected.
>> >
>> > Maybe there are broker configuration items which can affect this.
>> > If
>> so, I
>> > hope that someone knowledgeable will speak up. But I doubt that
>> > this is the problem.
>> >
>> > Are you sure that your subprocess runs? It might be trying to
>> > report an error to you. Of, if you have pipes configured for
>> > interaction with the invoking processor, it might be waiting on one of those.
>> >
>> > You could, temporarily, instead of your intended code, have the
>> subprocess
>> > invoke something like BasicHTTPServer, and see if you can interact
>> > with
>> it
>> > using your browser. If that also fails, it leaves the broker
>> > connection out as the source of your problems.
>> >
>> > Possibly easier is to have it log its arrival at various points, so
>> > you
>> can
>> > be sure where it is getting stuck. If you've already confirmed
>> > that
>> it's
>> > in the broker connect, forgive me, and wait for a better answer.
>> >
>> > Bill
>> >
>> >
>> > On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor
>> > <teagy@blackbirdtech.com
>> > >wrote:
>> >
>> > > Hello,
>> > >
>> > >
>> > >
>> > > I'm having an issue connecting multiple Python subprocesses to
>> > > the
>> qpid
>> > > C++ broker. I have a main Python process that imports
>> > > C++ qpid.messaging
>> at
>> > the
>> > > top and spawns a few multiprocessing.Process objects that try to
>> create a
>> > > Qpid connection to the broker. Before I spawn the processes
>> > > though,
>> the
>> > > main process creates a connection to the Qpid broker just fine,
>> > > but
>> all
>> > of
>> > > the subprocess code hangs when it trys to connect to the qpid broker.
>> I
>> > > know qpid is supposed to be multi-threaded, but what about
>> multiprocess
>> > > with Python? What could be causing the connections to hang from
>> > > the subprocesses? Is there some singleton object that isn't
>> > > getting
>> released
>> > > that's blocking the other subprocesses from connecting?
>> > >
>> > >
>> > >
>> > > Thanks,
>> > >
>> > > TJ
>> > >
>> >
>>
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@qpid.apache.org
For additional commands, e-mail: users-help@qpid.apache.org
Re: Python Connections Hang from Subprocesses
Posted by Bill Freeman <ke...@gmail.com>.
By the way, I presume that you know that you can have multiple sessions on
one connection?
On Wed, Aug 7, 2013 at 5:49 PM, Bill Freeman <ke...@gmail.com> wrote:
>
>
>
> On Wed, Aug 7, 2013 at 5:35 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
>
>> What O/S are you running this on?
>>
>>
>>
>> Ubuntu 12.04 LTS
>>
>> What does the code that spawns the subprocess look like?
>>
>>
>>
>> So my Process objects have a run() method that is called as the
>> subprocess.
>>
>
> Ok. Unless I miss my guess, this is not a subprocess. This is a thread.
> Your object is probably a subclass or threading.Thread, and you never
> import subprocess anywhere. If you ran "ps -alxww" in another terminal,
> there wouldn't be a line for more than one process.
>
>>
>>
>>
>> import qpid.messaging # at the top of the Python module
>>
>>
>>
>> def run():
>>
>> // some other non-qpid setup
>>
>>
>>
>> conn = qpid.messaging.Connection(qpid_endpoint)
>>
>> conn.open() <-- hangs here
>>
>> self.sess = conn.session()
>>
>> I have done this when there was already a connection to the broker, but
> that other connection was a qmf.console connection, which does not use
> qpid.messaging under the hood.
>
> Someone else will have to speak to the thread safety of qpid.messaging,
> because we have now exceeded my experience in that area.
>
>
>>
>> Can you, even when the subprocess is hung, run something like spout,
>> drain, or qpid-config, e.g.;
>>
>> qpid-config queues
>>
>> from another console window on the same box?
>>
>>
>>
>> Yes, I can connect to the queue if I try to connect from another module
>> (which runs a new copy of the Python interpreter).
>>
>> ________________________________
>> From: Bill Freeman [ke1g.nh@gmail.com]
>> Sent: Wednesday, August 07, 2013 4:21 PM
>> To: users
>> Subject: Re: Python Connections Hang from Subprocesses
>>
>> Just in case it makes me (or someone else) think of something else:
>>
>> What O/S are you running this on?
>>
>> What does the code that spawns the subprocess look like?
>>
>> Can you, even when the subprocess is hung, run something like spout,
>> drain, or qpid-config, e.g.;
>>
>> qpid-config queues
>>
>> from another console window on the same box?
>>
>> Bill
>>
>>
>> On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <teagy@blackbirdtech.com
>> >wrote:
>>
>> > Oops. Let me clean it up a bit.
>> >
>> > def attach(self):
>> >
>> > """
>> > Attach to the remote endpoint.
>> > """
>> > if not self._connected:
>> > self._connected = True
>> > self._driver.start()
>> > self._wakeup()
>> > self._ewait(lambda: self._transport_connected and not self._unlinked())
>> >
>> > def _ewait(self, predicate, timeout=None):
>> >
>> >
>> > result = self._wait(lambda: self.error or predicate(), timeout) <--
>> It
>> > times out here.
>> > self.check_error()
>> > return result
>> >
>> >
>> > ________________________________
>> > From: Eagy, Taylor [teagy@BlackbirdTech.com]
>> > Sent: Wednesday, August 07, 2013 2:50 PM
>> > To: users@qpid.apache.org
>> > Subject: RE: Python Connections Hang from Subprocesses
>> >
>> > Bill thanks for your response. The subprocess definitely runs when I
>> don't
>> > try to connect to the broker. Running a HTTPServer in it works too. It
>> just
>> > doesn't connect to the qpid broker. I did a little digging and I believe
>> > this is where it is hanging:
>> >
>> > (In Connection class)
>> >
>> > 270 @synchronized
>> >
>> > 271 -<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
>> >
>> > def attach<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach
>> > >(self):
>> >
>> > 272 """
>> > 273 Attach to the remote endpoint.
>> > 274 """
>> > 275 if not self._connected:
>> > 276 self._connected = True
>> > 277 self._driver.start<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
>> > >()
>> > 278 self._wakeup()
>> > 279 self._ewait(lambda: self._transport_connected and not
>> > self._unlinked())
>> >
>> > The parent Python process can connect successfully, but the
>> > self._transport_connected never gets set to True for all of the new
>> > Connection objects created in the subprocesses that are trying to
>> connect
>> > to the same broker. Where does this get set to True?
>> > Could this have something to do with the predicate because it doesn't
>> > return an error it just times out?
>> >
>> >
>> > 212 -<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
>> >
>> > def _ewait<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait
>> >(self,
>> > predicate, timeout=None):
>> >
>> > 213 result = self._wait(lambda: self.error or predicate(),
>> timeout<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
>> > >)
>> > 214 self.check_error<
>> >
>> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
>> > >()
>> > 215 return result
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > Thanks,
>> > Taylor
>> > ________________________________
>> > From: Bill Freeman [ke1g.nh@gmail.com]
>> > Sent: Wednesday, August 07, 2013 2:00 PM
>> > To: users
>> > Subject: Re: Python Connections Hang from Subprocesses
>> >
>> > Subprocesses (using the subprocess module, or even the older exec
>> stuff, as
>> > opposed to threads, or even forked clones) are relatively trouble free
>> in
>> > python (except maybe on Windows, whose process model has that Microsoft
>> > difference). I've certainly made multiple connections to a broker from
>> one
>> > python process, as well as using tools like spout and drain, which are
>> both
>> > written in python, while my main development project is running
>> connected.
>> >
>> > Maybe there are broker configuration items which can affect this. If
>> so, I
>> > hope that someone knowledgeable will speak up. But I doubt that this is
>> > the problem.
>> >
>> > Are you sure that your subprocess runs? It might be trying to report an
>> > error to you. Of, if you have pipes configured for interaction with the
>> > invoking processor, it might be waiting on one of those.
>> >
>> > You could, temporarily, instead of your intended code, have the
>> subprocess
>> > invoke something like BasicHTTPServer, and see if you can interact with
>> it
>> > using your browser. If that also fails, it leaves the broker connection
>> > out as the source of your problems.
>> >
>> > Possibly easier is to have it log its arrival at various points, so you
>> can
>> > be sure where it is getting stuck. If you've already confirmed that
>> it's
>> > in the broker connect, forgive me, and wait for a better answer.
>> >
>> > Bill
>> >
>> >
>> > On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <teagy@blackbirdtech.com
>> > >wrote:
>> >
>> > > Hello,
>> > >
>> > >
>> > >
>> > > I'm having an issue connecting multiple Python subprocesses to the
>> qpid
>> > > C++ broker. I have a main Python process that imports qpid.messaging
>> at
>> > the
>> > > top and spawns a few multiprocessing.Process objects that try to
>> create a
>> > > Qpid connection to the broker. Before I spawn the processes though,
>> the
>> > > main process creates a connection to the Qpid broker just fine, but
>> all
>> > of
>> > > the subprocess code hangs when it trys to connect to the qpid broker.
>> I
>> > > know qpid is supposed to be multi-threaded, but what about
>> multiprocess
>> > > with Python? What could be causing the connections to hang from the
>> > > subprocesses? Is there some singleton object that isn't getting
>> released
>> > > that's blocking the other subprocesses from connecting?
>> > >
>> > >
>> > >
>> > > Thanks,
>> > >
>> > > TJ
>> > >
>> >
>>
>
>
Re: Python Connections Hang from Subprocesses
Posted by Bill Freeman <ke...@gmail.com>.
On Wed, Aug 7, 2013 at 5:35 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> What O/S are you running this on?
>
>
>
> Ubuntu 12.04 LTS
>
> What does the code that spawns the subprocess look like?
>
>
>
> So my Process objects have a run() method that is called as the subprocess.
>
Ok. Unless I miss my guess, this is not a subprocess. This is a thread.
Your object is probably a subclass or threading.Thread, and you never
import subprocess anywhere. If you ran "ps -alxww" in another terminal,
there wouldn't be a line for more than one process.
>
>
>
> import qpid.messaging # at the top of the Python module
>
>
>
> def run():
>
> // some other non-qpid setup
>
>
>
> conn = qpid.messaging.Connection(qpid_endpoint)
>
> conn.open() <-- hangs here
>
> self.sess = conn.session()
>
> I have done this when there was already a connection to the broker, but
that other connection was a qmf.console connection, which does not use
qpid.messaging under the hood.
Someone else will have to speak to the thread safety of qpid.messaging,
because we have now exceeded my experience in that area.
>
> Can you, even when the subprocess is hung, run something like spout,
> drain, or qpid-config, e.g.;
>
> qpid-config queues
>
> from another console window on the same box?
>
>
>
> Yes, I can connect to the queue if I try to connect from another module
> (which runs a new copy of the Python interpreter).
>
> ________________________________
> From: Bill Freeman [ke1g.nh@gmail.com]
> Sent: Wednesday, August 07, 2013 4:21 PM
> To: users
> Subject: Re: Python Connections Hang from Subprocesses
>
> Just in case it makes me (or someone else) think of something else:
>
> What O/S are you running this on?
>
> What does the code that spawns the subprocess look like?
>
> Can you, even when the subprocess is hung, run something like spout,
> drain, or qpid-config, e.g.;
>
> qpid-config queues
>
> from another console window on the same box?
>
> Bill
>
>
> On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <teagy@blackbirdtech.com
> >wrote:
>
> > Oops. Let me clean it up a bit.
> >
> > def attach(self):
> >
> > """
> > Attach to the remote endpoint.
> > """
> > if not self._connected:
> > self._connected = True
> > self._driver.start()
> > self._wakeup()
> > self._ewait(lambda: self._transport_connected and not self._unlinked())
> >
> > def _ewait(self, predicate, timeout=None):
> >
> >
> > result = self._wait(lambda: self.error or predicate(), timeout) <--
> It
> > times out here.
> > self.check_error()
> > return result
> >
> >
> > ________________________________
> > From: Eagy, Taylor [teagy@BlackbirdTech.com]
> > Sent: Wednesday, August 07, 2013 2:50 PM
> > To: users@qpid.apache.org
> > Subject: RE: Python Connections Hang from Subprocesses
> >
> > Bill thanks for your response. The subprocess definitely runs when I
> don't
> > try to connect to the broker. Running a HTTPServer in it works too. It
> just
> > doesn't connect to the qpid broker. I did a little digging and I believe
> > this is where it is hanging:
> >
> > (In Connection class)
> >
> > 270 @synchronized
> >
> > 271 -<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >
> > def attach<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach
> > >(self):
> >
> > 272 """
> > 273 Attach to the remote endpoint.
> > 274 """
> > 275 if not self._connected:
> > 276 self._connected = True
> > 277 self._driver.start<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> > >()
> > 278 self._wakeup()
> > 279 self._ewait(lambda: self._transport_connected and not
> > self._unlinked())
> >
> > The parent Python process can connect successfully, but the
> > self._transport_connected never gets set to True for all of the new
> > Connection objects created in the subprocesses that are trying to connect
> > to the same broker. Where does this get set to True?
> > Could this have something to do with the predicate because it doesn't
> > return an error it just times out?
> >
> >
> > 212 -<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >
> > def _ewait<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait
> >(self,
> > predicate, timeout=None):
> >
> > 213 result = self._wait(lambda: self.error or predicate(), timeout<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> > >)
> > 214 self.check_error<
> >
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> > >()
> > 215 return result
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Thanks,
> > Taylor
> > ________________________________
> > From: Bill Freeman [ke1g.nh@gmail.com]
> > Sent: Wednesday, August 07, 2013 2:00 PM
> > To: users
> > Subject: Re: Python Connections Hang from Subprocesses
> >
> > Subprocesses (using the subprocess module, or even the older exec stuff,
> as
> > opposed to threads, or even forked clones) are relatively trouble free in
> > python (except maybe on Windows, whose process model has that Microsoft
> > difference). I've certainly made multiple connections to a broker from
> one
> > python process, as well as using tools like spout and drain, which are
> both
> > written in python, while my main development project is running
> connected.
> >
> > Maybe there are broker configuration items which can affect this. If
> so, I
> > hope that someone knowledgeable will speak up. But I doubt that this is
> > the problem.
> >
> > Are you sure that your subprocess runs? It might be trying to report an
> > error to you. Of, if you have pipes configured for interaction with the
> > invoking processor, it might be waiting on one of those.
> >
> > You could, temporarily, instead of your intended code, have the
> subprocess
> > invoke something like BasicHTTPServer, and see if you can interact with
> it
> > using your browser. If that also fails, it leaves the broker connection
> > out as the source of your problems.
> >
> > Possibly easier is to have it log its arrival at various points, so you
> can
> > be sure where it is getting stuck. If you've already confirmed that it's
> > in the broker connect, forgive me, and wait for a better answer.
> >
> > Bill
> >
> >
> > On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <teagy@blackbirdtech.com
> > >wrote:
> >
> > > Hello,
> > >
> > >
> > >
> > > I'm having an issue connecting multiple Python subprocesses to the qpid
> > > C++ broker. I have a main Python process that imports qpid.messaging at
> > the
> > > top and spawns a few multiprocessing.Process objects that try to
> create a
> > > Qpid connection to the broker. Before I spawn the processes though, the
> > > main process creates a connection to the Qpid broker just fine, but all
> > of
> > > the subprocess code hangs when it trys to connect to the qpid broker. I
> > > know qpid is supposed to be multi-threaded, but what about multiprocess
> > > with Python? What could be causing the connections to hang from the
> > > subprocesses? Is there some singleton object that isn't getting
> released
> > > that's blocking the other subprocesses from connecting?
> > >
> > >
> > >
> > > Thanks,
> > >
> > > TJ
> > >
> >
>
RE: Python Connections Hang from Subprocesses
Posted by "Eagy, Taylor" <te...@BlackbirdTech.com>.
What O/S are you running this on?
Ubuntu 12.04 LTS
What does the code that spawns the subprocess look like?
So my Process objects have a run() method that is called as the subprocess.
import qpid.messaging # at the top of the Python module
def run():
// some other non-qpid setup
conn = qpid.messaging.Connection(qpid_endpoint)
conn.open() <-- hangs here
self.sess = conn.session()
Can you, even when the subprocess is hung, run something like spout,
drain, or qpid-config, e.g.;
qpid-config queues
from another console window on the same box?
Yes, I can connect to the queue if I try to connect from another module (which runs a new copy of the Python interpreter).
________________________________
From: Bill Freeman [ke1g.nh@gmail.com]
Sent: Wednesday, August 07, 2013 4:21 PM
To: users
Subject: Re: Python Connections Hang from Subprocesses
Just in case it makes me (or someone else) think of something else:
What O/S are you running this on?
What does the code that spawns the subprocess look like?
Can you, even when the subprocess is hung, run something like spout,
drain, or qpid-config, e.g.;
qpid-config queues
from another console window on the same box?
Bill
On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Oops. Let me clean it up a bit.
>
> def attach(self):
>
> """
> Attach to the remote endpoint.
> """
> if not self._connected:
> self._connected = True
> self._driver.start()
> self._wakeup()
> self._ewait(lambda: self._transport_connected and not self._unlinked())
>
> def _ewait(self, predicate, timeout=None):
>
>
> result = self._wait(lambda: self.error or predicate(), timeout) <-- It
> times out here.
> self.check_error()
> return result
>
>
> ________________________________
> From: Eagy, Taylor [teagy@BlackbirdTech.com]
> Sent: Wednesday, August 07, 2013 2:50 PM
> To: users@qpid.apache.org
> Subject: RE: Python Connections Hang from Subprocesses
>
> Bill thanks for your response. The subprocess definitely runs when I don't
> try to connect to the broker. Running a HTTPServer in it works too. It just
> doesn't connect to the qpid broker. I did a little digging and I believe
> this is where it is hanging:
>
> (In Connection class)
>
> 270 @synchronized
>
> 271 -<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>
> def attach<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach
> >(self):
>
> 272 """
> 273 Attach to the remote endpoint.
> 274 """
> 275 if not self._connected:
> 276 self._connected = True
> 277 self._driver.start<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >()
> 278 self._wakeup()
> 279 self._ewait(lambda: self._transport_connected and not
> self._unlinked())
>
> The parent Python process can connect successfully, but the
> self._transport_connected never gets set to True for all of the new
> Connection objects created in the subprocesses that are trying to connect
> to the same broker. Where does this get set to True?
> Could this have something to do with the predicate because it doesn't
> return an error it just times out?
>
>
> 212 -<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>
> def _ewait<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait>(self,
> predicate, timeout=None):
>
> 213 result = self._wait(lambda: self.error or predicate(), timeout<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >)
> 214 self.check_error<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >()
> 215 return result
>
>
>
>
>
>
>
>
>
> Thanks,
> Taylor
> ________________________________
> From: Bill Freeman [ke1g.nh@gmail.com]
> Sent: Wednesday, August 07, 2013 2:00 PM
> To: users
> Subject: Re: Python Connections Hang from Subprocesses
>
> Subprocesses (using the subprocess module, or even the older exec stuff, as
> opposed to threads, or even forked clones) are relatively trouble free in
> python (except maybe on Windows, whose process model has that Microsoft
> difference). I've certainly made multiple connections to a broker from one
> python process, as well as using tools like spout and drain, which are both
> written in python, while my main development project is running connected.
>
> Maybe there are broker configuration items which can affect this. If so, I
> hope that someone knowledgeable will speak up. But I doubt that this is
> the problem.
>
> Are you sure that your subprocess runs? It might be trying to report an
> error to you. Of, if you have pipes configured for interaction with the
> invoking processor, it might be waiting on one of those.
>
> You could, temporarily, instead of your intended code, have the subprocess
> invoke something like BasicHTTPServer, and see if you can interact with it
> using your browser. If that also fails, it leaves the broker connection
> out as the source of your problems.
>
> Possibly easier is to have it log its arrival at various points, so you can
> be sure where it is getting stuck. If you've already confirmed that it's
> in the broker connect, forgive me, and wait for a better answer.
>
> Bill
>
>
> On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <teagy@blackbirdtech.com
> >wrote:
>
> > Hello,
> >
> >
> >
> > I'm having an issue connecting multiple Python subprocesses to the qpid
> > C++ broker. I have a main Python process that imports qpid.messaging at
> the
> > top and spawns a few multiprocessing.Process objects that try to create a
> > Qpid connection to the broker. Before I spawn the processes though, the
> > main process creates a connection to the Qpid broker just fine, but all
> of
> > the subprocess code hangs when it trys to connect to the qpid broker. I
> > know qpid is supposed to be multi-threaded, but what about multiprocess
> > with Python? What could be causing the connections to hang from the
> > subprocesses? Is there some singleton object that isn't getting released
> > that's blocking the other subprocesses from connecting?
> >
> >
> >
> > Thanks,
> >
> > TJ
> >
>
Re: Python Connections Hang from Subprocesses
Posted by Bill Freeman <ke...@gmail.com>.
Just in case it makes me (or someone else) think of something else:
What O/S are you running this on?
What does the code that spawns the subprocess look like?
Can you, even when the subprocess is hung, run something like spout,
drain, or qpid-config, e.g.;
qpid-config queues
from another console window on the same box?
Bill
On Wed, Aug 7, 2013 at 3:13 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Oops. Let me clean it up a bit.
>
> def attach(self):
>
> """
> Attach to the remote endpoint.
> """
> if not self._connected:
> self._connected = True
> self._driver.start()
> self._wakeup()
> self._ewait(lambda: self._transport_connected and not self._unlinked())
>
> def _ewait(self, predicate, timeout=None):
>
>
> result = self._wait(lambda: self.error or predicate(), timeout) <-- It
> times out here.
> self.check_error()
> return result
>
>
> ________________________________
> From: Eagy, Taylor [teagy@BlackbirdTech.com]
> Sent: Wednesday, August 07, 2013 2:50 PM
> To: users@qpid.apache.org
> Subject: RE: Python Connections Hang from Subprocesses
>
> Bill thanks for your response. The subprocess definitely runs when I don't
> try to connect to the broker. Running a HTTPServer in it works too. It just
> doesn't connect to the qpid broker. I did a little digging and I believe
> this is where it is hanging:
>
> (In Connection class)
>
> 270 @synchronized
>
> 271 -<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>
> def attach<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach
> >(self):
>
> 272 """
> 273 Attach to the remote endpoint.
> 274 """
> 275 if not self._connected:
> 276 self._connected = True
> 277 self._driver.start<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >()
> 278 self._wakeup()
> 279 self._ewait(lambda: self._transport_connected and not
> self._unlinked())
>
> The parent Python process can connect successfully, but the
> self._transport_connected never gets set to True for all of the new
> Connection objects created in the subprocesses that are trying to connect
> to the same broker. Where does this get set to True?
> Could this have something to do with the predicate because it doesn't
> return an error it just times out?
>
>
> 212 -<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>
> def _ewait<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait>(self,
> predicate, timeout=None):
>
> 213 result = self._wait(lambda: self.error or predicate(), timeout<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >)
> 214 self.check_error<
> http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#
> >()
> 215 return result
>
>
>
>
>
>
>
>
>
> Thanks,
> Taylor
> ________________________________
> From: Bill Freeman [ke1g.nh@gmail.com]
> Sent: Wednesday, August 07, 2013 2:00 PM
> To: users
> Subject: Re: Python Connections Hang from Subprocesses
>
> Subprocesses (using the subprocess module, or even the older exec stuff, as
> opposed to threads, or even forked clones) are relatively trouble free in
> python (except maybe on Windows, whose process model has that Microsoft
> difference). I've certainly made multiple connections to a broker from one
> python process, as well as using tools like spout and drain, which are both
> written in python, while my main development project is running connected.
>
> Maybe there are broker configuration items which can affect this. If so, I
> hope that someone knowledgeable will speak up. But I doubt that this is
> the problem.
>
> Are you sure that your subprocess runs? It might be trying to report an
> error to you. Of, if you have pipes configured for interaction with the
> invoking processor, it might be waiting on one of those.
>
> You could, temporarily, instead of your intended code, have the subprocess
> invoke something like BasicHTTPServer, and see if you can interact with it
> using your browser. If that also fails, it leaves the broker connection
> out as the source of your problems.
>
> Possibly easier is to have it log its arrival at various points, so you can
> be sure where it is getting stuck. If you've already confirmed that it's
> in the broker connect, forgive me, and wait for a better answer.
>
> Bill
>
>
> On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <teagy@blackbirdtech.com
> >wrote:
>
> > Hello,
> >
> >
> >
> > I'm having an issue connecting multiple Python subprocesses to the qpid
> > C++ broker. I have a main Python process that imports qpid.messaging at
> the
> > top and spawns a few multiprocessing.Process objects that try to create a
> > Qpid connection to the broker. Before I spawn the processes though, the
> > main process creates a connection to the Qpid broker just fine, but all
> of
> > the subprocess code hangs when it trys to connect to the qpid broker. I
> > know qpid is supposed to be multi-threaded, but what about multiprocess
> > with Python? What could be causing the connections to hang from the
> > subprocesses? Is there some singleton object that isn't getting released
> > that's blocking the other subprocesses from connecting?
> >
> >
> >
> > Thanks,
> >
> > TJ
> >
>
RE: Python Connections Hang from Subprocesses
Posted by "Eagy, Taylor" <te...@BlackbirdTech.com>.
Oops. Let me clean it up a bit.
def attach(self):
"""
Attach to the remote endpoint.
"""
if not self._connected:
self._connected = True
self._driver.start()
self._wakeup()
self._ewait(lambda: self._transport_connected and not self._unlinked())
def _ewait(self, predicate, timeout=None):
result = self._wait(lambda: self.error or predicate(), timeout) <-- It times out here.
self.check_error()
return result
________________________________
From: Eagy, Taylor [teagy@BlackbirdTech.com]
Sent: Wednesday, August 07, 2013 2:50 PM
To: users@qpid.apache.org
Subject: RE: Python Connections Hang from Subprocesses
Bill thanks for your response. The subprocess definitely runs when I don't try to connect to the broker. Running a HTTPServer in it works too. It just doesn't connect to the qpid broker. I did a little digging and I believe this is where it is hanging:
(In Connection class)
270 @synchronized
271 -<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#> def attach<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach>(self):
272 """
273 Attach to the remote endpoint.
274 """
275 if not self._connected:
276 self._connected = True
277 self._driver.start<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>()
278 self._wakeup()
279 self._ewait(lambda: self._transport_connected and not self._unlinked())
The parent Python process can connect successfully, but the self._transport_connected never gets set to True for all of the new Connection objects created in the subprocesses that are trying to connect to the same broker. Where does this get set to True?
Could this have something to do with the predicate because it doesn't return an error it just times out?
212 -<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#> def _ewait<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait>(self, predicate, timeout=None):
213 result = self._wait(lambda: self.error or predicate(), timeout<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>)
214 self.check_error<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>()
215 return result
Thanks,
Taylor
________________________________
From: Bill Freeman [ke1g.nh@gmail.com]
Sent: Wednesday, August 07, 2013 2:00 PM
To: users
Subject: Re: Python Connections Hang from Subprocesses
Subprocesses (using the subprocess module, or even the older exec stuff, as
opposed to threads, or even forked clones) are relatively trouble free in
python (except maybe on Windows, whose process model has that Microsoft
difference). I've certainly made multiple connections to a broker from one
python process, as well as using tools like spout and drain, which are both
written in python, while my main development project is running connected.
Maybe there are broker configuration items which can affect this. If so, I
hope that someone knowledgeable will speak up. But I doubt that this is
the problem.
Are you sure that your subprocess runs? It might be trying to report an
error to you. Of, if you have pipes configured for interaction with the
invoking processor, it might be waiting on one of those.
You could, temporarily, instead of your intended code, have the subprocess
invoke something like BasicHTTPServer, and see if you can interact with it
using your browser. If that also fails, it leaves the broker connection
out as the source of your problems.
Possibly easier is to have it log its arrival at various points, so you can
be sure where it is getting stuck. If you've already confirmed that it's
in the broker connect, forgive me, and wait for a better answer.
Bill
On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Hello,
>
>
>
> I'm having an issue connecting multiple Python subprocesses to the qpid
> C++ broker. I have a main Python process that imports qpid.messaging at the
> top and spawns a few multiprocessing.Process objects that try to create a
> Qpid connection to the broker. Before I spawn the processes though, the
> main process creates a connection to the Qpid broker just fine, but all of
> the subprocess code hangs when it trys to connect to the qpid broker. I
> know qpid is supposed to be multi-threaded, but what about multiprocess
> with Python? What could be causing the connections to hang from the
> subprocesses? Is there some singleton object that isn't getting released
> that's blocking the other subprocesses from connecting?
>
>
>
> Thanks,
>
> TJ
>
RE: Python Connections Hang from Subprocesses
Posted by "Eagy, Taylor" <te...@BlackbirdTech.com>.
Bill thanks for your response. The subprocess definitely runs when I don't try to connect to the broker. Running a HTTPServer in it works too. It just doesn't connect to the qpid broker. I did a little digging and I believe this is where it is hanging:
(In Connection class)
270 @synchronized
271 -<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#> def attach<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#attach>(self):
272 """
273 Attach to the remote endpoint.
274 """
275 if not self._connected:
276 self._connected = True
277 self._driver.start<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>()
278 self._wakeup()
279 self._ewait(lambda: self._transport_connected and not self._unlinked())
The parent Python process can connect successfully, but the self._transport_connected never gets set to True for all of the new Connection objects created in the subprocesses that are trying to connect to the same broker. Where does this get set to True?
Could this have something to do with the predicate because it doesn't return an error it just times out?
212 -<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#> def _ewait<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints.Connection-class.html#_ewait>(self, predicate, timeout=None):
213 result = self._wait(lambda: self.error or predicate(), timeout<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>)
214 self.check_error<http://qpid.apache.org/releases/qpid-0.22/messaging-api/python/api/qpid.messaging.endpoints-pysrc.html#>()
215 return result
Thanks,
Taylor
________________________________
From: Bill Freeman [ke1g.nh@gmail.com]
Sent: Wednesday, August 07, 2013 2:00 PM
To: users
Subject: Re: Python Connections Hang from Subprocesses
Subprocesses (using the subprocess module, or even the older exec stuff, as
opposed to threads, or even forked clones) are relatively trouble free in
python (except maybe on Windows, whose process model has that Microsoft
difference). I've certainly made multiple connections to a broker from one
python process, as well as using tools like spout and drain, which are both
written in python, while my main development project is running connected.
Maybe there are broker configuration items which can affect this. If so, I
hope that someone knowledgeable will speak up. But I doubt that this is
the problem.
Are you sure that your subprocess runs? It might be trying to report an
error to you. Of, if you have pipes configured for interaction with the
invoking processor, it might be waiting on one of those.
You could, temporarily, instead of your intended code, have the subprocess
invoke something like BasicHTTPServer, and see if you can interact with it
using your browser. If that also fails, it leaves the broker connection
out as the source of your problems.
Possibly easier is to have it log its arrival at various points, so you can
be sure where it is getting stuck. If you've already confirmed that it's
in the broker connect, forgive me, and wait for a better answer.
Bill
On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Hello,
>
>
>
> I'm having an issue connecting multiple Python subprocesses to the qpid
> C++ broker. I have a main Python process that imports qpid.messaging at the
> top and spawns a few multiprocessing.Process objects that try to create a
> Qpid connection to the broker. Before I spawn the processes though, the
> main process creates a connection to the Qpid broker just fine, but all of
> the subprocess code hangs when it trys to connect to the qpid broker. I
> know qpid is supposed to be multi-threaded, but what about multiprocess
> with Python? What could be causing the connections to hang from the
> subprocesses? Is there some singleton object that isn't getting released
> that's blocking the other subprocesses from connecting?
>
>
>
> Thanks,
>
> TJ
>
Re: Python Connections Hang from Subprocesses
Posted by Bill Freeman <ke...@gmail.com>.
Subprocesses (using the subprocess module, or even the older exec stuff, as
opposed to threads, or even forked clones) are relatively trouble free in
python (except maybe on Windows, whose process model has that Microsoft
difference). I've certainly made multiple connections to a broker from one
python process, as well as using tools like spout and drain, which are both
written in python, while my main development project is running connected.
Maybe there are broker configuration items which can affect this. If so, I
hope that someone knowledgeable will speak up. But I doubt that this is
the problem.
Are you sure that your subprocess runs? It might be trying to report an
error to you. Of, if you have pipes configured for interaction with the
invoking processor, it might be waiting on one of those.
You could, temporarily, instead of your intended code, have the subprocess
invoke something like BasicHTTPServer, and see if you can interact with it
using your browser. If that also fails, it leaves the broker connection
out as the source of your problems.
Possibly easier is to have it log its arrival at various points, so you can
be sure where it is getting stuck. If you've already confirmed that it's
in the broker connect, forgive me, and wait for a better answer.
Bill
On Wed, Aug 7, 2013 at 12:55 PM, Eagy, Taylor <te...@blackbirdtech.com>wrote:
> Hello,
>
>
>
> I'm having an issue connecting multiple Python subprocesses to the qpid
> C++ broker. I have a main Python process that imports qpid.messaging at the
> top and spawns a few multiprocessing.Process objects that try to create a
> Qpid connection to the broker. Before I spawn the processes though, the
> main process creates a connection to the Qpid broker just fine, but all of
> the subprocess code hangs when it trys to connect to the qpid broker. I
> know qpid is supposed to be multi-threaded, but what about multiprocess
> with Python? What could be causing the connections to hang from the
> subprocesses? Is there some singleton object that isn't getting released
> that's blocking the other subprocesses from connecting?
>
>
>
> Thanks,
>
> TJ
>