JMAP(1)

💅 JMAP(1) — the jmap page, but make it make sense

okay so real talk: this is the man page for jmap, and it lives in the JDK Commands section of the manual. It's a tool that prints details about a process you specify, and bestie, it's experimental and unsupported — so treat it like a cute vintage find, not a load-bearing wall. 🫶

✨ NAME ✨

jmap — print details of a specified process. that's it, that's the whole vibe check. 💖

🌸 SYNOPSIS 🌸

⚠️ heads up before anything else: This command is experimental and unsupported. no cap.

jmap [options] pid

• options — this is where you put the jmap command-line options. peek at Options for the jmap Command below for the full menu, menu-obsessed icon that you are. 🍓
• pid — the process ID you want the info printed for. important: the process must be a Java process. to get a list of Java processes running on a machine, use either the ps command or — and this is the fun conditional — the jps command, if the JVM processes are not running in a separate docker instance. iykyk. 🐳

🦋 DESCRIPTION 🦋

The jmap command prints details of a specified running process. literally that's the job. 💅

Note:

This command is unsupported and might not be available in future releases of the JDK. 😭 So don't build your whole personality around it, okay?

On Windows systems where the dbgeng.dll file isn't present, the Debugging Tools for Windows must be installed to make these tools work. and listen — 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. both of those? path stuff. treat it right. ✨

🎀 OPTIONS FOR THE JMAP COMMAND 🎀

• -clstats pid — connects to a running process and prints class loader statistics of the Java heap. class loader lore, honestly iconic. 👑
• -finalizerinfo pid — connects to a running process and prints information on objects awaiting finalization. the ones in limbo. the ones not yet at peace. 💀
• -histo[:live] pid — connects to a running process and prints a histogram of the Java object heap. if you specify the live suboption, it then counts only live objects. so -histo = everyone invited, -histo:live = strict guest list. 🙈
• -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. main character objects vs. the whole crowd. 🌈
  • format=b — dumps the Java heap in hprof binary format.
  • file=filename — dumps the heap to filename.

Example, so you can copy-paste and slay:

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

and that's the whole page, bestie, no crumbs left behind 🧚💜

⭐ cute little sign-off ⭐ — this gorgeousness is from JDK 25.0.5.0.3, dated 2026. screenshot it, frame it, put it on your wall. 🎀💖