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javamemory-leaksjvmheap-dump

Issue Taking Java Heap Dump

I'm trying to take a java heap dump to help investigate a memory leak. Whenever I use this:

 jmap -J-d64 -dump:format=b,file=myheapdump -F 29498

The heap dump file gets to about 16,048 kb and stops growing, jmap will run forever and not stop unless I kill it. Alternatively I tried using this:

jcmd 29498 -F GC.heap_dump heapdump.hprof

But since I am executing it from root, and the process is being run from another user, I get this:

com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded
    at sun.tools.attach.LinuxVirtualMachine.<init>(LinuxVirtualMachine.java:106)
    at sun.tools.attach.LinuxAttachProvider.attachVirtualMachine(LinuxAttachProvider.java:63)
    at com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:208)
    at sun.tools.jcmd.JCmd.executeCommandForPid(JCmd.java:147)
    at sun.tools.jcmd.JCmd.main(JCmd.java:131)

So I guess my question is what am I doing wrong and what is the best way to move forward in trying to get this heap dump?

Solution

  • To get around the error when using jcmd, you can try adding the jvm argument mentioned in this answer: com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded

    Another possibility if you're using Linux is to use the gdb tool as outlined here: https://www.atlassian.com/blog/archives/so-you-want-your-jvms-heap