When jmap fails to attach to a target process, it prints:
"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"

However, there are other options that the user should consider first:
- Run jmap under the same user account which runs the target process.
- Run jmap against a core dump file to produce a heap dump.

Having these suggestions right in front of you in the error message would save less experienced users time finding out what to to.