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Jmap command is specially used to trace memory mapping of process. jmap prints shared object memory maps or heap memory details of a given process or core file or a remote debug server. Man page of the jmap command also useful to get idea about commands use. If the given process is running on a 64-bit VM, you may need to specify the -J-d64 option, e.g.:
jmap -J-d64 -heap pid
jmap [ option ] pid
jmap [ option ] executable core
jmap [ option ] [server-id@]remote-hostname-or-IP
Options are mutually exclusive. Option, if used, should follow immediately after the command name.
Process id for which the memory map is to be printed. The process must be a Java process. To get a list of Java processes running on a machine, jps may be used.
Java executable from which the core dump was produced.
Core file for which the memory map is to be printed.
Remote debug server's (see jsadebugd) hostname or IP address.
Optional unique id, if multiple debug servers are running on the same remote host.
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When no option is used jmap prints shared object mappings. For each shared object loaded in the target VM, start address, the size of the mapping, and the full path of the shared object file are printed. This is similar to the Solaris pmap utility. You can see the output of this command at this link : Check Java Process Performance and statistics in Linux
Dumps the Java heap in hprof binary format to filename. The live suboption is optional. If specified, only the live objects in the heap are dumped. To browse the heap dump, you can use jhat (Java Heap Analysis Tool) to read the generated file.
Prints information on objects awaiting finalization.
Prints a heap summary. GC algorithm used, heap configuration and generation wise heap usage are printed.
Prints a histogram of the heap. For each Java class, number of objects, memory size in bytes, and fully qualified class names are printed. VM internal class names are printed with prefix. If the live suboption is specified, only live objects are counted.
Prints class loader wise statistics of permanent generation of Java heap. For each class loader, its name, liveness, address, parent class loader, and the number and size of classes it has loaded are printed. In addition, the number and size of interned Strings are printed. Using this option if you want to see the output then click here: Check Java Process Performance and statistics in Linux
Use with jmap -dump or jmap -histo option if the pid does not respond. The live suboption is not supported in this mode.
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