Techienote com wrote:
On Tue, Apr 16, 2013 at 12:33 PM, Pïd stèr <p...@pidster.com> wrote:
On 16 Apr 2013, at 06:35, Techienote com <techienote....@gmail.com> wrote:
Hi Team,
Recently I am seeing concurrent mode failure errors in my Verbose GC
logs.
For the same I have set NewSize to 512MB, still I am seeing concurrent
mode
failure in the Verbose GC logs
Where have you set these JVM attributes and how are you starting Tomcat?
Is the log below from after you set NewSize to 512 or before? It
doesn't look like it is set to me.
After changing the NewSize to 512. Can you please confirm how you come to
know that the size is not set.
What does your app do?
This is document uploading and authorizing applicaton.
When did this start happening, was it after a specific app update?
I am seeing this after changing the default policy to CMS
Have you observed load increasing due to user activity?
Concurrent # of users are 12
Regards,
Vidyadhar
p
62230.611: [ParNew (promotion failed)
Desired survivor size 32768 bytes, new threshold 0 (max 0)
: 28481K->28481K(28608K), 0.0483728 secs]62230.659: [CMS (concurrent mode
failure)
Also Garbage collection is causing some large pauses. The largest pause
was
121239 ms.
: 1255376K->215461K(2068480K), 121.1880176 secs]
1283830K->215461K(2097088K)Heap after gc invocations=12320:
par new generation total 28608K, used 0K [0x68800000, 0x6a400000,
0x6a400000)
eden space 28544K, 0% used [0x68800000, 0x68800000, 0x6a3e0000)
from space 64K, 0% used [0x6a3e0000, 0x6a3e0000, 0x6a3f0000)
to space 64K, 0% used [0x6a3f0000, 0x6a3f0000, 0x6a400000)
concurrent mark-sweep generation total 2068480K, used 215461K
[0x6a400000,
0xe8800000, 0xe8800000)
concurrent-mark-sweep perm gen total 88496K, used 55091K [0xe8800000,
0xede6c000, 0xf8800000)
}
, 121.2390524 secs]
Following is my JVM argument
-server -verbose:gc -Xmx2048m -Xms2048m -XX:NewSize=512m
-XX:MaxNewSize=512m -XX:MaxPermSize=256M -XX:+UseConcMarkSweepGC
-XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled
-Dsun.rmi.dgc.client.gcInterval=3600000
-Dsun.rmi.dgc.server.gcInterval=3600000 -XX:+DisableExplicitGC
-XX:+HeapDumpOnOutOfMemoryError -XX:+HeapDumpOnCtrlBreak
-XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintClassHistogram
-XX:+PrintGCDetails -XX:+PrintTenuringDistribution
Tomcat Version
6.0.36
JDK Version
Sun HotSpot 1.5.0.22
CPU
Number of Physical processor 1
Number of Virtual processor 7
RAM
6144MB
OS
SunOS 5.10 Generic_147440-09 sun4v sparc sun4v
Do you have any idea how to tune it further?
I think that the question should be asked : with an application that has only 12
concurrent users, is there any particular reason why you *need* to specifiy all these
parameters ?
By default, without any of these memory and GC-related parameters, the JVM will use
default values which are pre-tuned by real specialists to be *reasonable* for most
applications.
I run about 20 Tomcat servers, with a variety of applications and loads. The only
non-default parameters I ever specify, other than for specific debugging, are "-Xms" and
"-Xmx", and these servers are doing fine as far as I can tell.
By specifying all these parameters, is it possible that you are in fact doing the very
opposite from "tuning", and that you are completely "de-tuning" the JVM ?
If you just remove them all, and specify only
"-Xmx2048m -Xms2048m", what happens ?
"Premature optimization is the root of all evil"
http://en.wikiquote.org/wiki/Donald_Knuth
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