Jmap can't connect to make a dump

The solution was very simple. I was running the jmap as root, but I had to run it as the user who started the jvm. I will now go hide my head in shame.

I was running the jmap and the application with the same user and still get the error.

The solution was run that comand before the jmap

echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

Than is just use jmap and will works fine

jmap -heap 17210

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

docker exec <container-name> 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

Future Googlers:

This could also happen if you installed the JDK while the process you're trying to jmap was running.

If that's the case, restart the java process.