Heap dump collection using Jrcmd command

To collect heap dump from jrcmd , we can use below command

jrcmd pid print_object_summery

Prints details of all the instances on the heap on a per-class basis, together with a differential value of how the memory usage has changed. Columns: a) Percentage of heap that objects of this class occupy, b) The total size occupied by the instances of a specific class, c) The number of instances of a specific class, d) The change in size from the first invocation of this command, e) The full name of the class. Check the next sample run, where we might have a problem with objects of class


/usr/java/jrockit-28.2.5/bin/jrcmd 18138 print_object_summary > heapdump

example out put like this:

 18138:

--------- Detailed Heap Statistics: ---------
40.5% 1336739k 31856677     +0k [C
23.2% 764694k  2569326     +0k [Ljava/lang/Object;
22.7% 749887k 31995192     +0k java/lang/String
 2.6% 84918k   776395     +0k atg/adapter/gsa/GSAItem
 1.5% 50745k    42095    +11k [B
 0.9% 29182k  1245133     +0k java/util/HashMap$Entry
 0.9% 28747k  1839867     +0k java/lang/Double
 0.8% 26071k   129558     +0k [Ljava/util/HashMap$Entry;
 0.7% 22059k  1411807     +0k java/lang/Integer
 0.6% 18175k   775504     +0k atg/adapter/gsa/SingleValueGSAId
 0.5% 18021k   768916     +0k atg/core/util/SmallHashMap
 0.5% 17195k   550244     +0k java/sql/Timestamp
     3299105kB total ---

--------- End of Detailed Heap Statistics ---






If you want to check threadump using Jrcmd check here:

Thread dumps using jrockit

We can take the thread dumps using unix command as

kill -3 pid

or we can get thread dumps using admin console. (on privious posts i already explained)

Here i am going to get thred dump using JROCKIT , jrcmd command

jrcmd pid print_threads > thread.out_file


jrcmd 30654 print_threads > /logs/thread.out


here 30654 is process id.

print_threads: it redirects  thread logs into mentioned out log file.(as per example /logs/thread.out)