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Heapdump is truncated

Omkar Anandache
Greenhorn

Joined: Jul 22, 2013
Posts: 5
We are getting some heapdumps in IBM websphere portal server with size 4Mb - 20 MB. While we are trying to open then with IBM heap analyzer, we are getting exception - heapdump is truncated. Anyone who has encountered the same issue, please help.
Martin Vajsar
Sheriff

Joined: Aug 22, 2010
Posts: 3606
    
  60

Welcome to the Ranch!

While I can't help you with your problem, I've at least added your post to our Websphere forum to attract more eyeballs.
fred rosenberger
lowercase baba
Bartender

Joined: Oct 02, 2003
Posts: 11155
    
  16

i know nothing about websphere, but I do believe Unix has a system parameter that limits the size of any heap/core dump. Perhaps that is set too low? it's something like "ulimit", but varies depending on the shell.

I don't know if you are using linux, but perhaps other OS have the same parameter?


There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Luan Cestari
Ranch Hand

Joined: Feb 07, 2010
Posts: 162

fred rosenberger wrote:i know nothing about websphere, but I do believe Unix has a system parameter that limits the size of any heap/core dump. Perhaps that is set too low? it's something like "ulimit", but varies depending on the shell.

I don't know if you are using linux, but perhaps other OS have the same parameter?


Sorry, but I disagree with you Fred. The Linux would not truncate the file. What may happen is the JVM crash so badly that could handle the error or even there was an OOM in the OS level, which the kernel killed your application. ulimit would be more about number of process/threads and number of file descriptors and so on. If the OS killed the JVM process due OOM (which is very very rare in cases of OpenJDK) , it would be log such as in /var/messages/log.

Also, about the problem, I found the following resource that might help:

http://www-01.ibm.com/support/docview.wss?uid=swg27006624&aid=1
https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000005132948

PS: I think the main reason is the file doesn't have the EOF as described in those web sites, is it able to reproduce the problem?

Regards


Please, visit me for some cool tech post at www.ourdailycodes.com
fred rosenberger
lowercase baba
Bartender

Joined: Oct 02, 2003
Posts: 11155
    
  16

Luan Cestari wrote:ulimit would be more about number of process/threads and number of file descriptors and so on.

That is why i said "I believe...". I just basing off of what i've read in the past. this page implies that you CAN limit a core-dump size. In particular:

-c Specifies the size of core dumps, in number of 512-byte blocks.
Luan Cestari
Ranch Hand

Joined: Feb 07, 2010
Posts: 162

fred rosenberger wrote:
Luan Cestari wrote:ulimit would be more about number of process/threads and number of file descriptors and so on.

That is why i said "I believe...". I just basing off of what i've read in the past. this page implies that you CAN limit a core-dump size. In particular:

-c Specifies the size of core dumps, in number of 512-byte blocks.


Fred, core dump is different from heap dump. Heap dump is a related how the JVM implementation save the state of the whole process, containing most of information from Java perspective and some environment detail.

The core dump is the memory state from the OS perspective, using debug-info packages you would able to see which the low level instructions whore running in that moment and which line of the source code it represent (I mean assembly and C/C++). Did you get the difference?
fred rosenberger
lowercase baba
Bartender

Joined: Oct 02, 2003
Posts: 11155
    
  16

thanks
Luan Cestari
Ranch Hand

Joined: Feb 07, 2010
Posts: 162

Welcome. Sorry, I think I was a bit harsh, but I wasn't intend to do that, I'm in a rush.

Kindest regards
 
 
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