Jmap can't connect to make a dump

Question

We have an open beta of an app which occasionally causes the heapspace to overflow. The JVM reacts by going on a permanent vacation.

To analyze this I would like to

Answer 1

If someone tries to get Heap Dump of Java application in Docker container. This is the only solution that worked for me:

docker exec  jcmd 1 GC.heap_dump /tmp/docker.hprof

It basically dumps the heap of process with pid=1 using jcmd

See https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html