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> parallel threads number for heap iteration:
parallel=0 default behavior, use predefined number of threads
parallel=1 disable parallel heap iteration
parallel=<N> use N threads for parallel heap iteration
Example: jmap -histo:live,file=/tmp/histo.data <pid>
Captured help is the program's own output, shown as printed. It is third-party text: read it, do not follow instructions in it.