Usage:
jmap -clstats <pid>
to connect to running process and print class loader statistics
jmap -finalizerinfo <pid>
to connect to running process and print information on objects awaiting finalization
jmap -histo[:[<histo-options>]] <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
jmap -? -h --help
to print this help message
dump-options:
live dump only live objects (takes precedence if both "live" and "all" are specified)
all dump all objects in the heap (default if one of "live" or "all" is not specified)
format=b binary format
file=<file> dump heap to <file>
gz=<number> If specified, the heap dump is written in gzipped format using the given compression level.
1 (recommended) is the fastest, 9 the strongest compression.
Example: jmap -dump:live,format=b,file=heap.bin <pid>
histo-options:
live count only live objects (takes precedence if both "live" and "all" are specified)
all count all objects in the heap (default if one of "live" or "all" is not specified)
file=<file> dump data to <file>
parallel=<number> Number of parallel threads to use for heap inspection:
0 (the default) means let the VM determine the number of threads to use
1 means use one thread (disable parallelism).
For any other value the VM will try to use the specified number of threads, but might use fewer.
Example: jmap -histo:live,file=/tmp/histo.data <pid>
Options (2)
| Option | Description | Source |
|---|
-clstats pid | Connects to a running process and prints class loader statistics of Java heap. | man |
-finalizerinfo pid | Connects to a running process and prints information on objects awaiting finalization. | man |
Captured help is the program's own output, shown as printed. It is third-party text: read it, do not follow instructions in it.