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Posted to users@tomcat.apache.org by Patrick Plaatje <pa...@ipros.nl> on 2009/03/11 11:02:50 UTC
"hanging" threads on Tomcat
Hi all,
on one of our websites we have a problem with threads keep hanging in
Tomcat. We first noticed this 1.5 week ago and tried several things to
find a solution. At that moment we were using java 1.4 and Tomcat 5.0.
The symptoms were there after three hours of operation, about 250
threads were hanging within tomcat, and they seemed to be waiting for
"something".
After a week we realised we needed more information whihc we couldn't
get from the current setup, we upgraded the three production application
servers to be Java 1.5 and Tomcat 5.5.25. All three servers still have
the same problem, although the problem now has an interval of appr. 6
hours instead of three.
During the hanging of the threads we made 8 threaddumps. But i am unsure
of how to "read" the thread dumps. A small overview of the state of the
threads:
- 309 threads overall
- Threads waiting for monitors: 57
- Threads sleeping on monitors: 191
- Threads locking monitors: 225
- Monitors: 225
- Monitors without locking threads: 3
Can somebody please help me figuring out what the cause is, or how to
find the cause of the problem?
Best regards,
Patrick
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Re: "hanging" threads on Tomcat
Posted by Oliver Schoett <ol...@capgemini-sdm.com>.
Patrick Plaatje wrote:
> Thanks for the swift replies, i have two dump, appr a few seconds
> apart uploaded to:
>
> http://www.ipros.nl/uploads/catalina_stripped_1.out
> http://www.ipros.nl/uploads/catalina_stripped_2.out
Many threads appear to be waiting on the same instance of
org.apache.tomcat.dbcp.pool.impl.GenericObjectPool in
org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection, while I can
see only 4 threads actually doing database work.
Is it possible that you have configured too few database connections?
(If the current limit is 4, try 20.)
A second point of contention looks like
at neo.util.Mutex.aquire(Mutex.java:77)
at
neo.xredsys.presentation.ArticlePresentationManager.getArticle(ArticlePresentationManager.java:200)
at
neo.xredsys.presentation.ArticlePresentationManager.getArticle(ArticlePresentationManager.java:169)
at
neo.xredsys.presentation.ArticlePresentationManager.getArticle(ArticlePresentationManager.java:149)
But this may be a property of the software you use and harder to change.
Regards,
Oliver Schoett
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RE: "hanging" threads on Tomcat
Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: Patrick Plaatje [mailto:patrick@ipros.nl]
> Subject: Re: "hanging" threads on Tomcat
>
> Thanks for the swift replies, i have two dump, appr a few
> seconds apart uploaded to:
You appear to be out of database connections. This is almost always caused by webapp code not disposing of result sets, statements, and connections properly, leading to exhaustion of the pool. The proper technique is to insure that every place that obtains a connection also has a finally block that will close all the resources associated with the connection, including the connection itself.
This is a common discussion topic, so you can search the archives for examples. Also look at the Tomcat doc for recommended practice and how to detect (and work around) lost connections:
http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html
- Chuck
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Re: "hanging" threads on Tomcat
Posted by Patrick Plaatje <pa...@ipros.nl>.
Thanks for the swift replies, i have two dump, appr a few seconds apart
uploaded to:
http://www.ipros.nl/uploads/catalina_stripped_1.out
http://www.ipros.nl/uploads/catalina_stripped_2.out
Thanx,
Patrick
Mark Thomas schreef:
> Patrick Plaatje wrote:
>
>> Hi all,
>>
>> on one of our websites we have a problem with threads keep hanging in
>> Tomcat. We first noticed this 1.5 week ago and tried several things to
>> find a solution. At that moment we were using java 1.4 and Tomcat 5.0.
>> The symptoms were there after three hours of operation, about 250
>> threads were hanging within tomcat, and they seemed to be waiting for
>> "something".
>>
>> After a week we realised we needed more information whihc we couldn't
>> get from the current setup, we upgraded the three production application
>> servers to be Java 1.5 and Tomcat 5.5.25. All three servers still have
>> the same problem, although the problem now has an interval of appr. 6
>> hours instead of three.
>>
>> During the hanging of the threads we made 8 threaddumps. But i am unsure
>> of how to "read" the thread dumps. A small overview of the state of the
>> threads:
>>
>> - 309 threads overall
>> - Threads waiting for monitors: 57
>> - Threads sleeping on monitors: 191
>> - Threads locking monitors: 225
>> - Monitors: 225
>> - Monitors without locking threads: 3
>>
>> Can somebody please help me figuring out what the cause is, or how to
>> find the cause of the problem?
>>
>
> You'll need to provide the thread dumps. Rather than all 8, just two ~15s apart
> should suffice.
>
> Mark
>
>
>> Best regards,
>>
>> Patrick
>>
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>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>> For additional commands, e-mail: users-help@tomcat.apache.org
>>
>>
>
>
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>
>
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Re: "hanging" threads on Tomcat
Posted by Mark Thomas <ma...@apache.org>.
Patrick Plaatje wrote:
> Hi all,
>
> on one of our websites we have a problem with threads keep hanging in
> Tomcat. We first noticed this 1.5 week ago and tried several things to
> find a solution. At that moment we were using java 1.4 and Tomcat 5.0.
> The symptoms were there after three hours of operation, about 250
> threads were hanging within tomcat, and they seemed to be waiting for
> "something".
>
> After a week we realised we needed more information whihc we couldn't
> get from the current setup, we upgraded the three production application
> servers to be Java 1.5 and Tomcat 5.5.25. All three servers still have
> the same problem, although the problem now has an interval of appr. 6
> hours instead of three.
>
> During the hanging of the threads we made 8 threaddumps. But i am unsure
> of how to "read" the thread dumps. A small overview of the state of the
> threads:
>
> - 309 threads overall
> - Threads waiting for monitors: 57
> - Threads sleeping on monitors: 191
> - Threads locking monitors: 225
> - Monitors: 225
> - Monitors without locking threads: 3
>
> Can somebody please help me figuring out what the cause is, or how to
> find the cause of the problem?
You'll need to provide the thread dumps. Rather than all 8, just two ~15s apart
should suffice.
Mark
>
> Best regards,
>
> Patrick
>
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> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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>
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RE: "hanging" threads on Tomcat
Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: Patrick Plaatje [mailto:patrick@ipros.nl]
> Subject: "hanging" threads on Tomcat
>
> - 309 threads overall
> - Threads waiting for monitors: 57
> - Threads sleeping on monitors: 191
> - Threads locking monitors: 225
> - Monitors: 225
> - Monitors without locking threads: 3
Haven't looked at your thread dumps yet, but you might try using JConsole; it has an interesting looking "Detect Deadlocks" button on the Threads tab that may show you something useful.
- Chuck
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