JMAP(1)

🌸 jmap — the vibe-check edition 🌸

okay so bestie, welcome to the JMAP(1) page from the JDK Commands lineup. this is all about jmap, and yes, the manual name is literally JMAP(1). let's get into it 💅

✨ NAME ✨

jmap — print details of a specified process.

🦋 SYNOPSIS 🦋

Note: This command is experimental and unsupported.

jmap [options] pid

• options — this represents the jmap command-line options. See Options for the jmap Command.
• pid — the process ID for which the information specified by the options is to be printed. The process must be a Java process. To get a list of Java processes running on a machine, use either the ps command or, if the JVM processes are not running in a separate docker instance, the jps command.

💖 DESCRIPTION 💖

The jmap command prints details of a specified running process.

Note: This command is unsupported and might not be available in future releases of the JDK. On Windows Systems where the dbgeng.dll file isn't present, the Debugging Tools for Windows must be installed to make these tools work. The PATH environment variable should contain the location of the jvm.dll file that's used by the target process or the location from which the core dump file was produced.

🎀 OPTIONS FOR THE JMAP COMMAND 🎀

• -clstats pid — connects to a running process and prints class loader statistics of Java heap.
• -finalizerinfo pid — connects to a running process and prints information on objects awaiting finalization.
• -histo[:live] pid — connects to a running process and prints a histogram of the Java object heap. If the live suboption is specified, it then counts only live objects.
• -dump:dump_options pid — connects to a running process and dumps the Java heap. The dump_options include:
  • live — when specified, dumps only the live objects; if not specified, then dumps all objects in the heap.
  • format=b — Dumps the Java heap in hprof binary format.
  • file=filename — Dumps the heap to filename.

Example:

jmap -dump:live,format=b,file=heap.bin pid

xoxo, signing off from the JDK 23 source/version, dated 2024, on the JMAP(1) page. mwah 💖🎀🦋