Receiving error message "Error attaching to process: Doesn't appear to be a HotSpot VM (could not find symbol "gHotSpotVMTypes" when trying to execute jstack command

What are you trying to accomplish:

Execute a thread dump to troubleshoot an unresponsive druid process. 

Workaround or Solution:

Run the command as the linux user that is running the process.  For instance,

ps -f | grep java 

[root@localhost ~]# ps -ef | grep java

root      2341  2318  0 14:41 ?        00:00:19 java -server -Xms128m -Xmx128m -Duser.timezone=UTC -cp /tmp/imply-2.7.8/bin/../dist/zk/lib/*:/tmp/imply-2.7.8/bin/../dist/zk/*:/tmp/imply-2.7.8/conf-quickstart/zk org.apache.zookeeper.server.quorum.QuorumPeerMain /tmp/imply-2.7.8/conf-quickstart/zk/zoo.cfg

Based on this output, you can see that the root user is running the process.  Hence, in order to run the jstack command, you will need to be logged in as this user. 

Root Cause:

Executing the command with a linux user that isn't the same as the user running the druid process.