Jruby Heap Dump Failure

Question

I am running an APP using Jruby and Puma. We have an issue with a potential memory leak and I would like to generate a heap dump so that I can debug. My local environment is running Linux Mint 17. I have run the following:

jmap -histo:live 6450

and this resulted in :

6450: Unable to open socket file: target process not responding or HotSpot VM not loaded  The -F option can be used when the target process is not responding

I've also tried this:

jmap -dump:live,format=b,file=heap.bin 6450

result

6450: Unable to open socket file: target process not responding or HotSpot VM not loaded

As the propmt suggested I tried running with the -F flag:

jmap -F -dump:live,format=b,file=heap.bin 6450
Attaching to process ID 6450, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02
Dumping heap to heap.bin ...
Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.tools.jmap.JMap.runTool(JMap.java:201)
at sun.tools.jmap.JMap.main(JMap.java:130)
Caused by: sun.jvm.hotspot.utilities.AssertionFailure: can not get class     data for java/lang/UNIXProcess$Platform$$Lambda$10x0000000100393428
at sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.writeInstance(HeapHprofBinWriter.java:803)
at sun.jvm.hotspot.utilities.AbstractHeapGraphWriter$1.doObj(AbstractHeapGraphWriter.java:95)
at sun.jvm.hotspot.oops.ObjectHeap.iterateLiveRegions(ObjectHeap.java:353)
at sun.jvm.hotspot.oops.ObjectHeap.iterate(ObjectHeap.java:171)
at sun.jvm.hotspot.utilities.AbstractHeapGraphWriter.write(AbstractHeapGraphWriter.java:51)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.write(HeapHprofBinWriter.java:433)
at sun.jvm.hotspot.tools.HeapDumper.run(HeapDumper.java:62)
at sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:260)
at sun.jvm.hotspot.tools.Tool.start(Tool.java:223)
at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
at sun.jvm.hotspot.tools.HeapDumper.main(HeapDumper.java:83)
... 6 more`

Does anyone have any suggestions as to how to get around these errors and generate a heap dump ? I have tried using jvisualvm and Eclipse Memory Analyzer to generate a heap dump as well, and I run into the same issue.

Answer 1

This looks like a JVM bug in jdk 1.8_45 see this link for more info

https://bugs.openjdk.java.net/browse/JDK-8065318