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Posted to httpclient-users@hc.apache.org by Sajith Dilshan <sa...@gmail.com> on 2014/03/26 18:30:25 UTC
outputReady method in IOEventDispatcher
Hi everyone,
When I set the OP_WRITE event on a particular instance of
org.apache.http.nio.reactor.IOSession, a worker thread will pick up that
IOSession and will execute the outputReady(IOSession session) method of the
respective org.apache.http.nio.reactor.IOEventDispatch implementation.
My question is that, is it possible for more than one thread to execute
outputReady(IOSession session) method for the same instance of IOSession at
the same time? Does a worker thread acquires a lock before executing
outputReady(IOSession session) method for a particular IOSession instance?
Regards,
Sajith Dilshan
Re: outputReady method in IOEventDispatcher
Posted by Sajith Dilshan <sa...@gmail.com>.
> It is also guaranteed by the framework that only one I/O dispatch
> thread can interact with the same I/O session at a time.
That is what I wanted to know. Thank you very much Oleg.
On Thu, Mar 27, 2014 at 2:49 PM, Oleg Kalnichevski <ol...@apache.org> wrote:
> On Thu, 2014-03-27 at 14:13 +0530, Sajith Dilshan wrote:
> > Hi Oleg,
> >
> > Thank you for the reply. But I'm still a bit confused about the answer.
> So
> > let me rephrase my question. When a worker thread enters
> > outputReady(IOSession session) method with that session object, does that
> > worker thread acquires a lock on OP_WRITE operation for that particular
> > session object so that any other worker thread can't perform OP_WRITE
> > operation on that session object?
> >
>
> Only I/O event dispatch threads managed by the I/O reactor should ever
> call IOEventDispatch#outputReady. It is also guaranteed by the framework
> that only one I/O dispatch thread can interact with the same I/O session
> at a time.
>
> If your application create additional worker threads those threads
> should never call IOEventDispatch#outputReady. They should only interact
> with IOSession, update its state but let the I/O dispatch threads do the
> actual reading and writing.
>
> > As an example, assume there are two worker threads, Thread_A and
> Thread_B.
> > Further, there is a IOSession object session_123 with its event set as
> > OP_WRITE. Both threads, Thread_A and Thread_B see that OP_WRITE event is
> > set for session_123 and can the both threads (Thread_A, Thread_B) enter
> the
> > outputReady(IOSession session) method at the same time with the
> session_123
> > being the parameter passed to that method and execute the method's body?
> >
>
> See above. Worker threads should update IOSession's state (such as
> shared I/O buffer) but the actual writing should be performed by the I/O
> dispatch thread.
>
> There is a section on asynchronous I/O control for HTTP connections you
> may find useful:
>
>
> http://hc.apache.org/httpcomponents-core-4.3.x/tutorial/html/nio.html#d5e614
>
> Oleg
>
> >
> > On Thu, Mar 27, 2014 at 1:52 PM, Oleg Kalnichevski <ol...@apache.org>
> wrote:
> >
> > > On Wed, 2014-03-26 at 23:00 +0530, Sajith Dilshan wrote:
> > > > Hi everyone,
> > > >
> > > > When I set the OP_WRITE event on a particular instance of
> > > > org.apache.http.nio.reactor.IOSession, a worker thread will pick up
> that
> > > > IOSession and will execute the outputReady(IOSession session) method
> of
> > > the
> > > > respective org.apache.http.nio.reactor.IOEventDispatch
> implementation.
> > > >
> > > > My question is that, is it possible for more than one thread to
> execute
> > > > outputReady(IOSession session) method for the same instance of
> IOSession
> > > at
> > > > the same time?
> > >
> > > it is possible on multi CPU core systems.
> > >
> > > > Does a worker thread acquires a lock before executing
> > > > outputReady(IOSession session) method for a particular IOSession
> > > instance?
> > > >
> > >
> > > Yes, it does. Access to IOSession's internal structures is
> synchronized.
> > > IOSession-s are fully thread safe.
> > >
> > > Oleg
> > >
> > >
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: httpclient-users-unsubscribe@hc.apache.org
> > > For additional commands, e-mail: httpclient-users-help@hc.apache.org
> > >
> > >
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: httpclient-users-unsubscribe@hc.apache.org
> For additional commands, e-mail: httpclient-users-help@hc.apache.org
>
>
Re: outputReady method in IOEventDispatcher
Posted by Oleg Kalnichevski <ol...@apache.org>.
On Thu, 2014-03-27 at 14:13 +0530, Sajith Dilshan wrote:
> Hi Oleg,
>
> Thank you for the reply. But I'm still a bit confused about the answer. So
> let me rephrase my question. When a worker thread enters
> outputReady(IOSession session) method with that session object, does that
> worker thread acquires a lock on OP_WRITE operation for that particular
> session object so that any other worker thread can't perform OP_WRITE
> operation on that session object?
>
Only I/O event dispatch threads managed by the I/O reactor should ever
call IOEventDispatch#outputReady. It is also guaranteed by the framework
that only one I/O dispatch thread can interact with the same I/O session
at a time.
If your application create additional worker threads those threads
should never call IOEventDispatch#outputReady. They should only interact
with IOSession, update its state but let the I/O dispatch threads do the
actual reading and writing.
> As an example, assume there are two worker threads, Thread_A and Thread_B.
> Further, there is a IOSession object session_123 with its event set as
> OP_WRITE. Both threads, Thread_A and Thread_B see that OP_WRITE event is
> set for session_123 and can the both threads (Thread_A, Thread_B) enter the
> outputReady(IOSession session) method at the same time with the session_123
> being the parameter passed to that method and execute the method's body?
>
See above. Worker threads should update IOSession's state (such as
shared I/O buffer) but the actual writing should be performed by the I/O
dispatch thread.
There is a section on asynchronous I/O control for HTTP connections you
may find useful:
http://hc.apache.org/httpcomponents-core-4.3.x/tutorial/html/nio.html#d5e614
Oleg
>
> On Thu, Mar 27, 2014 at 1:52 PM, Oleg Kalnichevski <ol...@apache.org> wrote:
>
> > On Wed, 2014-03-26 at 23:00 +0530, Sajith Dilshan wrote:
> > > Hi everyone,
> > >
> > > When I set the OP_WRITE event on a particular instance of
> > > org.apache.http.nio.reactor.IOSession, a worker thread will pick up that
> > > IOSession and will execute the outputReady(IOSession session) method of
> > the
> > > respective org.apache.http.nio.reactor.IOEventDispatch implementation.
> > >
> > > My question is that, is it possible for more than one thread to execute
> > > outputReady(IOSession session) method for the same instance of IOSession
> > at
> > > the same time?
> >
> > it is possible on multi CPU core systems.
> >
> > > Does a worker thread acquires a lock before executing
> > > outputReady(IOSession session) method for a particular IOSession
> > instance?
> > >
> >
> > Yes, it does. Access to IOSession's internal structures is synchronized.
> > IOSession-s are fully thread safe.
> >
> > Oleg
> >
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: httpclient-users-unsubscribe@hc.apache.org
> > For additional commands, e-mail: httpclient-users-help@hc.apache.org
> >
> >
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Re: outputReady method in IOEventDispatcher
Posted by Sajith Dilshan <sa...@gmail.com>.
Hi Oleg,
Thank you for the reply. But I'm still a bit confused about the answer. So
let me rephrase my question. When a worker thread enters
outputReady(IOSession session) method with that session object, does that
worker thread acquires a lock on OP_WRITE operation for that particular
session object so that any other worker thread can't perform OP_WRITE
operation on that session object?
As an example, assume there are two worker threads, Thread_A and Thread_B.
Further, there is a IOSession object session_123 with its event set as
OP_WRITE. Both threads, Thread_A and Thread_B see that OP_WRITE event is
set for session_123 and can the both threads (Thread_A, Thread_B) enter the
outputReady(IOSession session) method at the same time with the session_123
being the parameter passed to that method and execute the method's body?
On Thu, Mar 27, 2014 at 1:52 PM, Oleg Kalnichevski <ol...@apache.org> wrote:
> On Wed, 2014-03-26 at 23:00 +0530, Sajith Dilshan wrote:
> > Hi everyone,
> >
> > When I set the OP_WRITE event on a particular instance of
> > org.apache.http.nio.reactor.IOSession, a worker thread will pick up that
> > IOSession and will execute the outputReady(IOSession session) method of
> the
> > respective org.apache.http.nio.reactor.IOEventDispatch implementation.
> >
> > My question is that, is it possible for more than one thread to execute
> > outputReady(IOSession session) method for the same instance of IOSession
> at
> > the same time?
>
> it is possible on multi CPU core systems.
>
> > Does a worker thread acquires a lock before executing
> > outputReady(IOSession session) method for a particular IOSession
> instance?
> >
>
> Yes, it does. Access to IOSession's internal structures is synchronized.
> IOSession-s are fully thread safe.
>
> Oleg
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: httpclient-users-unsubscribe@hc.apache.org
> For additional commands, e-mail: httpclient-users-help@hc.apache.org
>
>
Re: outputReady method in IOEventDispatcher
Posted by Oleg Kalnichevski <ol...@apache.org>.
On Wed, 2014-03-26 at 23:00 +0530, Sajith Dilshan wrote:
> Hi everyone,
>
> When I set the OP_WRITE event on a particular instance of
> org.apache.http.nio.reactor.IOSession, a worker thread will pick up that
> IOSession and will execute the outputReady(IOSession session) method of the
> respective org.apache.http.nio.reactor.IOEventDispatch implementation.
>
> My question is that, is it possible for more than one thread to execute
> outputReady(IOSession session) method for the same instance of IOSession at
> the same time?
it is possible on multi CPU core systems.
> Does a worker thread acquires a lock before executing
> outputReady(IOSession session) method for a particular IOSession instance?
>
Yes, it does. Access to IOSession's internal structures is synchronized.
IOSession-s are fully thread safe.
Oleg
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