Usage:
    jmap -histo <pid>
      (to connect to running process and print histogram of java object heap
    jmap -dump:<dump-options> <pid>
      (to connect to running process and dump java heap)

    dump-options:
      format=b     binary default
      file=<file>  dump heap to <file>

    Example:       jmap -dump:format=b,file=heap.bin <pid>