JHSDB(1) JDK Commands JHSDB(1)

# [NAME](#NAME)

jhsdb - attach to a Java process or launch a postmortem debugger to analyze the content of a core dump from a crashed Java Virtual Machine (JVM)

# [SYNOPSIS](#SYNOPSIS)

jhsdb clhsdb \[--pid *pid* | --exe *executable* --core *coredump*]

jhsdb hsdb \[--pid *pid* | --exe *executable* --core *coredump*]

jhsdb debugd (--pid *pid* | --exe *executable* --core *coredump*) \[*options*]

jhsdb jstack (--pid *pid* | --exe *executable* --core *coredump* | --connect *\[server-id@]debugd-host*) \[*options*]

jhsdb jmap (--pid *pid* | --exe *executable* --core *coredump* | --connect *\[server-id@]debugd-host*) \[*options*]

jhsdb jinfo (--pid *pid* | --exe *executable* --core *coredump* | --connect *\[server-id@]debugd-host*) \[*options*]

jhsdb jsnap (--pid *pid* | --exe *executable* --core *coredump* | --connect *\[server-id@]debugd-host*) \[*options*]

[*pid*](#pid)

The process ID to which the jhsdb tool should attach. The process must be a Java process. To get a list of Java processes running on a machine, use the ps command or, if the JVM processes are not running in a separate docker instance, the **jps** command.

[*executable*](#executable)

The Java executable file from which the core dump was produced.

[*coredump*](#coredump)

The core file to which the jhsdb tool should attach.

*\[server-id@]debugd-host*

An optional server ID and the address of the remote debug server (debugd).

[*options*](#options)

The command-line options for a jhsdb mode. See **Options for the debugd Mode**, **Options for the jstack** **Mode**, **Options for the jmap Mode**, **Options for the** **jinfo Mode**, and **Options for the jsnap Mode**.

**Note:**

Either the *pid* or the pair of *executable* and *core* files or the *\[server-id@]debugd-host* must be provided for debugd, jstack, jmap, jinfo and jsnap modes.

# [DESCRIPTION](#DESCRIPTION)

You can use the jhsdb tool to attach to a Java process or to launch a postmortem debugger to analyze the content of a core-dump from a crashed Java Virtual Machine (JVM). This command is experimental and unsupported.

**Note:**

Attaching the jhsdb tool to a live process will cause the process to hang and the process will probably crash when the debugger detaches.

The jhsdb tool can be launched in any one of the following modes:

jhsdb clhsdb

Starts the interactive command-line debugger.

jhsdb hsdb

Starts the interactive GUI debugger.

jhsdb debugd

Starts the remote debug server.

jhsdb jstack

Prints stack and locks information.

jhsdb jmap

Prints heap information.

jhsdb jinfo

Prints basic JVM information.

jhsdb jsnap

Prints performance counter information.

jhsdb *command* --help

Displays the options available for the *command*.

# [OPTIONS FOR THE DEBUGD MODE](#OPTIONS_FOR_THE_DEBUGD_MODE)

--serverid *server-id*

An optional unique ID for this debug server. This is required if multiple debug servers are run on the same machine.

--rmiport *port*

Sets the port number to which the RMI connector is bound. If not specified a random available port is used.

--registryport *port*

Sets the RMI registry port. This option overrides the system property 'sun.jvm.hotspot.rmi.port'. If not specified, the system property is used. If the system property is not set, the default port 1099 is used.

--hostname *hostname*

Sets the hostname the RMI connector is bound. The value could be a hostname or an IPv4/IPv6 address. This option overrides the system property 'java.rmi.server.hostname'. If not specified, the system property is used. If the system property is not set, a system hostname is used.

# [OPTIONS FOR THE JINFO MODE](#OPTIONS_FOR_THE_JINFO_MODE)

--flags

Prints the VM flags.

--sysprops

Prints the Java system properties.

[no option](#no)

Prints the VM flags and the Java system properties.

# [OPTIONS FOR THE JMAP MODE](#OPTIONS_FOR_THE_JMAP_MODE)

[no option](#no~2)

Prints the same information as Solaris pmap.

--heap

Prints the java heap summary.

--binaryheap

Dumps the java heap in hprof binary format.

--dumpfile *name*

The name of the dumpfile.

--histo

Prints the histogram of java object heap.

--clstats

Prints the class loader statistics.

--finalizerinfo

Prints the information on objects awaiting finalization.

# [OPTIONS FOR THE JSTACK MODE](#OPTIONS_FOR_THE_JSTACK_MODE)

--locks

Prints the java.util.concurrent locks information.

--mixed

Attempts to print both java and native frames if the platform allows it.

# [OPTIONS FOR THE JSNAP MODE](#OPTIONS_FOR_THE_JSNAP_MODE)

--all

Prints all performance counters.

2023 JDK 21

---

Document: jhsdb(1) from openjdk-21 21.0.12.1-r2 (Chainguard OS)
Source: https://github.com/openjdk/jdk21u.git