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Posted to users@tomcat.apache.org by "Cohen, Laurence" <lc...@novetta.com> on 2015/09/02 21:54:53 UTC
Help with Tomcat Applications not listening
Hi,
We have a webserver and an appserver, and the webserver talks to the
appserver on port 8007. Every once the communication will stop, and we
will notice an error on the webserver saying that it can't talk to the
appserver. When this happens, I will run a netstat -an |grep 8007 on the
appserver, and there are hundreds of connections to that port. When I
restart the app, it will be back to about 10 connections, and they will
start growing again.
I'm trying to figure out why they are growing so quickly, and why they
aren't dying when the connection is no longer needed.
Any help would be appreciated.
Thanks,
Larry Cohen
Re: Help with Tomcat Applications not listening
Posted by Mark Thomas <ma...@apache.org>.
On 02/09/2015 21:53, Cohen, Laurence wrote:
> Thank you Chris,
>
> We only have one webserver and two tomcat applications on the back end.
> Where do I set the connections allowed if we are using mod_proxy_httpd?
If this is the issue (and it is a good bet it is) the quick (and not
that dirty) solution is to switch to the NIO HTTP connector on the
Tomcat side.
Mark
>
> Thanks,
>
> Larry Cohen
>
> On Wed, Sep 2, 2015 at 4:47 PM, Christopher Schultz <
> chris@christopherschultz.net> wrote:
>
> Larry,
>
> On 9/2/15 3:54 PM, Cohen, Laurence wrote:
>>>> We have a webserver and an appserver, and the webserver talks to
>>>> the appserver on port 8007. Every once the communication will
>>>> stop, and we will notice an error on the webserver saying that it
>>>> can't talk to the appserver. When this happens, I will run a
>>>> netstat -an |grep 8007 on the appserver, and there are hundreds of
>>>> connections to that port. When I restart the app, it will be back
>>>> to about 10 connections, and they will start growing again.
>>>>
>>>> I'm trying to figure out why they are growing so quickly, and why
>>>> they aren't dying when the connection is no longer needed.
>
> My guess is that the number of connections coming from httpd and the
> number of connections allowed to Tomcat don't match up.
>
> How many web servers? How many back-end Tomcats? Which connector are
> you using?
>
> If w = # of httpd instances
> c = # of total httpd threads
> then you need w * c connections allowed in all of your Tomcats (see
> <Connector> attribute maxConnections.
>
> Another possibility is that the connection timeouts on httpd (mod_jk
> connect_timeout, in ms) versus Tomcat (<Connector> connectionTimeout,
> in ms) are not the same.
>
> -chris
>>
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Re: Help with Tomcat Applications not listening
Posted by Christopher Schultz <ch...@christopherschultz.net>.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256
Larry,
On 9/2/15 4:53 PM, Cohen, Laurence wrote:
> We only have one webserver and two tomcat applications on the back
> end. Where do I set the connections allowed if we are using
> mod_proxy_httpd?
So you have a single Tomcat server and a single web server?
No problem, but it's important to know:
1. Which httpd MPM you are using (prefork, event, etc.)
2. Which Tomcat connector you are using (BIO, NIO, APR)
- -chris
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Re: Help with Tomcat Applications not listening
Posted by "Cohen, Laurence" <lc...@novetta.com>.
Thank you Chris,
We only have one webserver and two tomcat applications on the back end.
Where do I set the connections allowed if we are using mod_proxy_httpd?
Thanks,
Larry Cohen
On Wed, Sep 2, 2015 at 4:47 PM, Christopher Schultz <
chris@christopherschultz.net> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> Larry,
>
> On 9/2/15 3:54 PM, Cohen, Laurence wrote:
> > We have a webserver and an appserver, and the webserver talks to
> > the appserver on port 8007. Every once the communication will
> > stop, and we will notice an error on the webserver saying that it
> > can't talk to the appserver. When this happens, I will run a
> > netstat -an |grep 8007 on the appserver, and there are hundreds of
> > connections to that port. When I restart the app, it will be back
> > to about 10 connections, and they will start growing again.
> >
> > I'm trying to figure out why they are growing so quickly, and why
> > they aren't dying when the connection is no longer needed.
>
> My guess is that the number of connections coming from httpd and the
> number of connections allowed to Tomcat don't match up.
>
> How many web servers? How many back-end Tomcats? Which connector are
> you using?
>
> If w = # of httpd instances
> c = # of total httpd threads
> then you need w * c connections allowed in all of your Tomcats (see
> <Connector> attribute maxConnections.
>
> Another possibility is that the connection timeouts on httpd (mod_jk
> connect_timeout, in ms) versus Tomcat (<Connector> connectionTimeout,
> in ms) are not the same.
>
> - -chris
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> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
--
[image: www.novetta.com]
Larry Cohen
System Administrator
12021 Sunset Hills Road, Suite 400
Reston, VA 20190
Email lcohen@novetta.com
Office 703-885-1064
Re: Help with Tomcat Applications not listening
Posted by Christopher Schultz <ch...@christopherschultz.net>.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256
Larry,
On 9/2/15 3:54 PM, Cohen, Laurence wrote:
> We have a webserver and an appserver, and the webserver talks to
> the appserver on port 8007. Every once the communication will
> stop, and we will notice an error on the webserver saying that it
> can't talk to the appserver. When this happens, I will run a
> netstat -an |grep 8007 on the appserver, and there are hundreds of
> connections to that port. When I restart the app, it will be back
> to about 10 connections, and they will start growing again.
>
> I'm trying to figure out why they are growing so quickly, and why
> they aren't dying when the connection is no longer needed.
My guess is that the number of connections coming from httpd and the
number of connections allowed to Tomcat don't match up.
How many web servers? How many back-end Tomcats? Which connector are
you using?
If w = # of httpd instances
c = # of total httpd threads
then you need w * c connections allowed in all of your Tomcats (see
<Connector> attribute maxConnections.
Another possibility is that the connection timeouts on httpd (mod_jk
connect_timeout, in ms) versus Tomcat (<Connector> connectionTimeout,
in ms) are not the same.
- -chris
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Re: Help with Tomcat Applications not listening
Posted by "Cohen, Laurence" <lc...@novetta.com>.
1. apache httpd 2.2.x
2. mod_proxy_httpd
3. I'll have to clean up this information.
4. 7.0.59, jdk 1.8u51
5. I'll have to clean up this information.
6. Yes, we have iptables running on both the app server and web server but
even when we shut them down we still have the problem.
I'll send 3 and 5 as soon as possible.
Thanks,
Larry
On Wed, Sep 2, 2015 at 4:39 PM, Mark Eggers <it...@yahoo.com.invalid>
wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Larry,
>
> On 9/2/2015 12:54 PM, Cohen, Laurence wrote:
> > Hi,
> >
> > We have a webserver and an appserver, and the webserver talks to
> > the appserver on port 8007. Every once the communication will
> > stop, and we will notice an error on the webserver saying that it
> > can't talk to the appserver. When this happens, I will run a
> > netstat -an |grep 8007 on the appserver, and there are hundreds of
> > connections to that port. When I restart the app, it will be back
> > to about 10 connections, and they will start growing again.
> >
> > I'm trying to figure out why they are growing so quickly, and why
> > they aren't dying when the connection is no longer needed.
> >
> > Any help would be appreciated.
> >
> > Thanks,
> >
> > Larry Cohen
> >
>
> Unfortunately, I don't have Pid's crystal ball. A little more
> information is needed.
>
> 1. web server information
> (platform, web server software, version)
> 2. method of web server - app server connection
> (mod_jk, mod_proxy_ajp, mod_proxy_http)
> 3. Configuration for the connection
> 4. Tomcat information
> (platform, Java, version)
> 5. Connector configuration
> 6. Any intervening firewalls that might try to be "helpful"
>
> I'm guessing that something is keeping the connections active, or that
> there are no timeouts configured.
>
> It could also be a DOS attack.
>
> What does your application do (in general)? Can you replicate this
> problem in a test environment simulating normal (expected) traffic?
>
> . . . lots of questions, not a lot of answers
> /mde/
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> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
--
[image: www.novetta.com]
Larry Cohen
System Administrator
12021 Sunset Hills Road, Suite 400
Reston, VA 20190
Email lcohen@novetta.com
Office 703-885-1064
Re: Help with Tomcat Applications not listening
Posted by Mark Eggers <it...@yahoo.com.INVALID>.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Larry,
On 9/2/2015 12:54 PM, Cohen, Laurence wrote:
> Hi,
>
> We have a webserver and an appserver, and the webserver talks to
> the appserver on port 8007. Every once the communication will
> stop, and we will notice an error on the webserver saying that it
> can't talk to the appserver. When this happens, I will run a
> netstat -an |grep 8007 on the appserver, and there are hundreds of
> connections to that port. When I restart the app, it will be back
> to about 10 connections, and they will start growing again.
>
> I'm trying to figure out why they are growing so quickly, and why
> they aren't dying when the connection is no longer needed.
>
> Any help would be appreciated.
>
> Thanks,
>
> Larry Cohen
>
Unfortunately, I don't have Pid's crystal ball. A little more
information is needed.
1. web server information
(platform, web server software, version)
2. method of web server - app server connection
(mod_jk, mod_proxy_ajp, mod_proxy_http)
3. Configuration for the connection
4. Tomcat information
(platform, Java, version)
5. Connector configuration
6. Any intervening firewalls that might try to be "helpful"
I'm guessing that something is keeping the connections active, or that
there are no timeouts configured.
It could also be a DOS attack.
What does your application do (in general)? Can you replicate this
problem in a test environment simulating normal (expected) traffic?
. . . lots of questions, not a lot of answers
/mde/
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Re: Help with Tomcat Applications not listening
Posted by je...@gmail.com.
Larry,
Make sure that you’re closing any resource that you’ve opened.
Jeff
Sent from Windows Mail
From: Cohen, Laurence
Sent: Wednesday, September 2, 2015 2:54 PM
To: Tomcat Users List
Hi,
We have a webserver and an appserver, and the webserver talks to the
appserver on port 8007. Every once the communication will stop, and we
will notice an error on the webserver saying that it can't talk to the
appserver. When this happens, I will run a netstat -an |grep 8007 on the
appserver, and there are hundreds of connections to that port. When I
restart the app, it will be back to about 10 connections, and they will
start growing again.
I'm trying to figure out why they are growing so quickly, and why they
aren't dying when the connection is no longer needed.
Any help would be appreciated.
Thanks,
Larry Cohen