C-heap memory leak of IceTea

Zhu Han schumi.han at gmail.com
Sat Dec 18 18:59:52 PST 2010


I might observe C-heap leak of IcedTea6 1.9.2 on Ubuntu 10.04. This bug was
reported against cassandra[1]. But I'm afraid it is a general openJDK
problem. Here is the symptoms. [1] may has more information on it.

For a infrequently accessed openJDK node, the memory usage is climbed up
every day, and I'm pretty sure it is not caused by leak on Java object heap.
This is the GC settings:

" /usr/bin/java -ea -Xms1G -Xmx1G -XX:+UseParNewGC -XX:+UseConcMarkSweepGC
-XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=1
-XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly
-XX:+HeapDumpOnOutOfMemoryError ..."

So the size of JVM heap is constant. Use pmap against the JVM process for
the last 3 days, I observed a region expanded every day. It can be expanded
to multiple gigabytes finally[1].

on 12/19: 00000000010c3000 178548K rw---    [ anon ]
on 12/18: 00000000010c3000 110320K rw---    [ anon ]
on 12/17: 00000000010c3000  39256K rw---    [ anon ]

I notice the region is on lower address of process address space. So I
suspect it is the c-heap of JVM. The map of object heap is as below, which
is constant in the last few days.

00002b58433c0000 1069824K rw---    [ anon ]

Both the heap and non-heap memory usage of java code is quite normal:

12/19/2010 10:56:13 +0800 org.archive.jmx.Client HeapMemoryUsage:
committed: 1065025536
init: 1073741824
max: 1065025536
used: 160743000

12/19/2010 10:56:23 +0800 org.archive.jmx.Client NonHeapMemoryUsage:
committed: 24313856
init: 24313856
max: 224395264
used: 20477424

There are hundreds of alive threads in the JVM.

12/19/2010 10:52:20 +0800 org.archive.jmx.Client PeakThreadCount: 244

 Originally, I suspect it is bug 6824570[2]. But After I upgraded JDK from
IceTea 1.8.2 to IceTea 1.9.2, the problem is still not fixed. [3] said it is
fixed in IceTea 1.9.0.

And there is another JVM instances running on the same node with ParNewGC
enabled, I did not observe the memory leak.  Although the peak thread count
is quite low of that instance, which is 43.

Do you have any hints to diagnostic this problem? I'd like to help.

[1] http://www.mail-archive.com/user@cassandra.apache.org/msg08063.html
[2] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6824570
[3] http://blog.fuseyism.com/index.php/2010/09/10/icedtea6-19-released/

best regards,
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