jmap does not finish dumping the Java heap and seems to hang.

Issue

We started to run jmap command in order to get a heap dump of a java software which had 31.415 GB heap memory.

# /usr/lib/jvm/java/bin/jmap -F -dump:live,format=b,file=/tmp/jmapdump1.prof 36745

However, jmap did not finish even after 8 hours. so we forced the command to stop.

Questions:

What is happening?

Are there another ways to get a heap dump ?