JDK-6413389 : jhat throws OOM while parsing large heapdumps
  • Type: Bug
  • Component: core-svc
  • Sub-Component: tools
  • Affected Version: 6
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2006-04-14
  • Updated: 2010-08-24
  • Resolved: 2006-04-29
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JDK 6
6 b83Fixed
Related Reports
Relates :  
JDK-6371746 - jhat: reduce heap requirement of jhat
Relates :  
JDK-6331662 - jhat: reduce memory by preferring iterator/enumeration instead of arrays
Relates :  
JDK-6326374 - jhat should read primitive array content lazily
Description
jhat throws OutOfMemoryError while parsing large heap dumps. It is important to reduce heap memory requirement of jhat as much as possible.
Comments
SUGGESTED FIX Webrev: http://bongo.india.sun.com/jhat/6413389/webrev/ Also refer to the attachment "webrev.tar"
24-04-2006
EVALUATION Using nio filemapping the heap dump may be memory mapped. In addition, sizes of all objects mirroring heap objects may be reduced by reading object content lazily. Objects can just have offset in the memory mapped buffer for content. Also, many fields such as stacktrace etc. can be moved out of JavaHeapObject.java to a side data structure in Snapshot.java (Maps) -- so that not every object needs storage (even for a null valued field)
14-04-2006