high thread count & garbage collection log

[ankur rathi]

How to understand GC (Garbage Collection) log?

It doesn't contain tiemlines. Suppose, thread count in my application was at high at a particular time, how can I figure out the root cause for it?

Any suggestions?

Thanks.

[ankur rathi]

It does have timelines of event. Following is a piece from GC log:

    
<CON[5509]: Concurrent collection, (25151968/1207958168) (115303184/134217576), 19775 ms since last CON or AF>
  <GC(12299): freeing class sun.reflect.GeneratedSerializationConstructorAccessor29443(83723c30)>
  <GC(12299): unloaded and freed 1 class>
<GC(12299): Bytes Traced =743283875 (Foreground: 183496068+ Background: 559787807) State = 2 >
  <GC(12299): GC cycle started Wed Feb  3 16:37:29 2010
  <GC(12299): heap layout:  (285895464/1207958168) (133678904/134217576)  /0>
  <GC(12299): freed 279119216 bytes, 31% free (419574368/1342175744), in 409 ms>
  <GC(12299): mark: 303 ms, sweep: 106 ms, compact: 0 ms>
  <GC(12299): refs: soft 48 (age >= 32), weak 199, final 719, phantom 0>
<CON[5509]: completed in 413 ms>

It says, GC cycle started Wed Feb 3 16:37:29 2010.

[ankur rathi]

Can anyone recommend a good, easy to understand GC log analyser tool? Thanks.

[Pushkar Choudhary]

Found this, this and this on Google. Not sure which one or if any one is easy to use / understand.