how to make heap dump

how to make gc heap dump

1. [marek@localhost bin]$ jcmd 8560 GC.heap_dump /tmp/test1.dump
    8560:
    Heap dump file created
2. Read file

[marek@localhost bin]$ jhat -port 7777 -J-mx4G /tmp/test1.dump
Reading from /tmp/test.dump...
Dump file created Mon Apr 07 15:04:00 CEST 2014
Snapshot read, resolving...
Resolving 819250 objects...
Chasing references, expect 163 dots...................................................................................................................................................................
Eliminating duplicate references...................................................................................................................................................................
Snapshot resolved.
Started HTTP server on port 7777
Server is ready.