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Huge heap dump files - takes hours to parse [message #4002] Wed, 03 September 2008 08:39 Go to next message
barak is currently offline barak
Messages: 5
Registered: July 2009
Junior Member
Hello all,

A servlet i'm running inside Tomcat occupies lots of memery (2G). Trying
to find out what makes the process so fat, I used jmap to create an heap
dump (live objects only). The produced file size is 1.5G. When I openned
this file in MemoryAnalyzer (60 minutes ago), it still parsing the file
(at least that what the GUI claims).

The ini file contains:
-vmargs
-Xmx2048m

The java version:

java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Server VM (build 1.6.0-b105, mixed mode)

The os is CentOS 5.

I'm using the last build of MemoryAnalyzer.

I'll appriciate any help,

Thanks,

Barak.
Re: Huge heap dump files - takes hours to parse [message #4006 is a reply to message #4002] Wed, 03 September 2008 09:30 Go to previous messageGo to next message
Krum Tsvetkov is currently offline Krum Tsvetkov
Messages: 149
Registered: July 2009
Senior Member
Hi,

Can you please look in the log file (<mat>/workspace/.metadata/.log) and
tell me how many objects the dump contains - there should be an INFO
severity log message about this.

The only thing I can think of which can make the parsing so slow is GC.
May be the objects are too much to be parsed with 2Gb, then it would make
sense to try with more heap (if the machine allows it).

Another reason for a very bad parse times could be that the box is
swapping. If the process memory doesn't fit in the physical memory and the
system starts to swap, then GC is really bad. I've seen sometimes single
GC run for an hour (well it was for much more heap).

Sorry I can't give you more hints for the moment. But it would be
interesting to know how many objects the dump contains.

krum
Re: Huge heap dump files - takes hours to parse [message #4071 is a reply to message #4006] Wed, 03 September 2008 09:44 Go to previous message
barak is currently offline barak
Messages: 5
Registered: July 2009
Junior Member
Hi,

This is the log file:

eclipse.buildId=unknown
java.version=1.6.0
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=linux, ARCH=x86, WS=gtk, NL=en_US
Command-line arguments: -os linux -ws gtk -arch x86

!ENTRY org.eclipse.mat.ui 1 0 2008-09-02 04:58:16.102
!MESSAGE Heap /workspace/development/org/eclipse/mat/srv1.bin contains
38,166,064 objects

Thanks for the tip, I'll check whether can I dedicate a stronger machine
to the parser.

Will let know you if something happens.

Barak.
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