Re: GC Issue on Tomcat6

2015-04-17 Thread David kerber

On 4/17/2015 8:32 AM, Subhro Paul wrote:

Hi Team,

For our client website we have two Tomcat servers. Both servers are having
same configuration which is 16GB RAM, 8CPUS and Linux 6.5 OS. Tomcat 6 and
JAVA 6 are installed in both systems.

Yesterday, using Jconsole we observed that frequency of GC on one server
was very high which was 5 GC hit per Minute and on other server it was 1
GC hit per 3 Minutes. But today we observed that on both of the servers GC
frequency is same.

Is this a know secnario or the server is facing any issue?


It was probably just receiving more traffic and/or doing more work of 
some other kind.



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Re: GC Issue on Tomcat6

2015-04-17 Thread Ameer Mawia
http://ca.linkedin.com/in/ameermawia
Toronto, ON
Phone:647-262-4380

On Fri, Apr 17, 2015 at 8:47 AM, David kerber dcker...@verizon.net wrote:

 On 4/17/2015 8:32 AM, Subhro Paul wrote:

 Hi Team,

 For our client website we have two Tomcat servers. Both servers are having
 same configuration which is 16GB RAM, 8CPUS and Linux 6.5 OS. Tomcat 6 and
 JAVA 6 are installed in both systems.

 Yesterday, using Jconsole we observed that frequency of GC on one server
 was very high which was 5 GC hit per Minute and on other server it was 1
 GC hit per 3 Minutes. But today we observed that on both of the servers GC
 frequency is same.

 Garbage Collection in Oracle Hot spot JVM takes place in generational
manner. GC on young generation is invoked much more frequently, while Full
GC is invoked once in a while. In any case, frequency is much higher than
what you have mentioned.

I'm not sure which GC(Young/Full) you are talking about? What pattern of GC
you have earlier observed?

 Is this a know secnario or the server is facing any issue?


 GC issue has nothing to do with Tomcat per say. It is the memory footprint
of your application which will dictate GC behavior.

In any case, if your application is facing some memory bottle-neck, it is
better to pay attention on the percentage your JVM is spending in GCing
your application. If that percentage is very high, say ~90%, that means
your application is facing sever memory constrain, your application is
almost stalled as JVM has been trying very high to recover some space. Most
probably in that case, your JVM will die throwing OOM error in sometime.


 It was probably just receiving more traffic and/or doing more work of some
 other kind.


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 To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
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Re: GC Issue on Tomcat6

2015-04-17 Thread Subhro Paul
From:   Ameer Mawia ameer.ma...@gmail.com
To: Tomcat Users List users@tomcat.apache.org
Date:   04/17/2015 06:29 PM
Subject:Re: GC Issue on Tomcat6



http://ca.linkedin.com/in/ameermawia
Toronto, ON
Phone:647-262-4380

On Fri, Apr 17, 2015 at 8:47 AM, David kerber dcker...@verizon.net 
wrote:

 On 4/17/2015 8:32 AM, Subhro Paul wrote:

 Hi Team,

 For our client website we have two Tomcat servers. Both servers are 
having
 same configuration which is 16GB RAM, 8CPUS and Linux 6.5 OS. Tomcat 6 
and
 JAVA 6 are installed in both systems.

 Yesterday, using Jconsole we observed that frequency of GC on one 
server
 was very high which was 5 GC hit per Minute and on other server it was 
1
 GC hit per 3 Minutes. But today we observed that on both of the servers 
GC
 frequency is same.

 Garbage Collection in Oracle Hot spot JVM takes place in generational
manner. GC on young generation is invoked much more frequently, while Full
GC is invoked once in a while. In any case, frequency is much higher than
what you have mentioned.

I'm not sure which GC(Young/Full) you are talking about? What pattern of 
GC
you have earlier observed?

 Is this a know secnario or the server is facing any issue?


 GC issue has nothing to do with Tomcat per say. It is the memory 
footprint
of your application which will dictate GC behavior.

In any case, if your application is facing some memory bottle-neck, it is
better to pay attention on the percentage your JVM is spending in GCing
your application. If that percentage is very high, say ~90%, that means
your application is facing sever memory constrain, your application is
almost stalled as JVM has been trying very high to recover some space. 
Most
probably in that case, your JVM will die throwing OOM error in sometime.


 It was probably just receiving more traffic and/or doing more work of 
some
 other kind.


 -
 To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
 For additional commands, e-mail: users-h...@tomcat.apache.org




Dear Ameer,

I am talking about Young GC which is PS Scavenge for both of the 
servers. Full GC was Running 1/Hour. Can you please assist how to check 
the % of memory utilization by GC through JConsole or any other process.

Thanks  Regards,
Subhro Paul
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Re: GC Issue on Tomcat6

2015-04-17 Thread Ameer Mawia
On Fri, Apr 17, 2015 at 10:07 AM, Subhro Paul subhro.p...@tcs.com wrote:

 From:   Ameer Mawia ameer.ma...@gmail.com
 To: Tomcat Users List users@tomcat.apache.org
 Date:   04/17/2015 06:29 PM
 Subject:Re: GC Issue on Tomcat6



 http://ca.linkedin.com/in/ameermawia
 Toronto, ON
 Phone:647-262-4380

 On Fri, Apr 17, 2015 at 8:47 AM, David kerber dcker...@verizon.net
 wrote:

  On 4/17/2015 8:32 AM, Subhro Paul wrote:
 
  Hi Team,
 
  For our client website we have two Tomcat servers. Both servers are
 having
  same configuration which is 16GB RAM, 8CPUS and Linux 6.5 OS. Tomcat 6
 and
  JAVA 6 are installed in both systems.
 
  Yesterday, using Jconsole we observed that frequency of GC on one
 server
  was very high which was 5 GC hit per Minute and on other server it was
 1
  GC hit per 3 Minutes. But today we observed that on both of the servers
 GC
  frequency is same.
 
  Garbage Collection in Oracle Hot spot JVM takes place in generational
 manner. GC on young generation is invoked much more frequently, while Full
 GC is invoked once in a while. In any case, frequency is much higher than
 what you have mentioned.

 I'm not sure which GC(Young/Full) you are talking about? What pattern of
 GC
 you have earlier observed?

  Is this a know secnario or the server is facing any issue?
 
 
  GC issue has nothing to do with Tomcat per say. It is the memory
 footprint
 of your application which will dictate GC behavior.

 In any case, if your application is facing some memory bottle-neck, it is
 better to pay attention on the percentage your JVM is spending in GCing
 your application. If that percentage is very high, say ~90%, that means
 your application is facing sever memory constrain, your application is
 almost stalled as JVM has been trying very high to recover some space.
 Most
 probably in that case, your JVM will die throwing OOM error in sometime.


  It was probably just receiving more traffic and/or doing more work of
 some
  other kind.
 
 
  -
  To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
  For additional commands, e-mail: users-h...@tomcat.apache.org
 
 


 Dear Ameer,

I am talking about Young GC which is PS Scavenge for both of the
 servers. Full GC was Running 1/Hour. Can you please assist how to check
 the % of memory utilization by GC through JConsole or any other process.

Subhro, please reply inline. People prefer that way here. It makes reading
the thread easier.

I was talking about percentage utilization of CPU Time by GC Threads.
Getting % Memory usage is also very helpful.

There is a number of way to check Memory utilization, stats:

   - JConsole Memory tab.
   - Console output. You will have to turn on the JVM flag to dump these
   details.
  - -XX:+PrintGCDetails -- This also give time spent in a particular GC
  operation.
  - Thread dump( Kill -3 Unix machine)

Also, you can get some fine tuned information about time usage by your
application threads, using these flags:

   - -XX:+PrintGCApplicationConcurrentTime
   -  -XX:+PrintGCApplicationStoppedTime

Out of curiosity, how did you get this information   Full GC was Running
1/Hour.

I guess that is too few run.



Thanks  Regards,
 Subhro Paul
 =-=-=
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 message and/or attachments to it may contain
 confidential or privileged information. If you are
 not the intended recipient, any dissemination, use,
 review, distribution, printing or copying of the
 information contained in this e-mail message
 and/or attachments to it are strictly prohibited. If
 you have received this communication in error,
 please notify us by reply e-mail or telephone and
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