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From Endre StĂžlsvik <En...@Stolsvik.com>
Subject RE: Memory Settings On Tomcat
Date Tue, 15 Jun 2004 16:26:45 GMT
On Tue, 15 Jun 2004, Shapira, Yoav wrote:

|
| Hi,
|
| >You might also want to try .gc() (force Garbage Collection) - run
| >freeMemory() right before and right after .gc(), print out the diff
| too.
|
| Man, I expect this error from novice posters, but not from you ;)

Oh, thanks..! ;)

| System.gc is ONLY A SUGGESTION.

I know - but Sun's VMs surely seems to follow your suggestions!

|  The more recent the JVM, the more likely it is to be ignored by the
| JVM, and moreover more and more admins/developers I know are setting
| -XX:+DisableExplicitGC as a Standard Operating Procedure.  Don't count
| on System.gc for anything.

Well, 1.5beta2 (that's rather recent, ai?) GC's like hell when I invoke
the method - it even seems to do it synchronous, as it (currentThread)
hangs while it does it..
  I only said this as an suggestion for seeing if you have tons of "dead
objects" lying around - you might be able to figure something out based on
the diff. On my system, I get a considerable diff after some time, but I
feel this is expected. A worse thing is that after each restart of my app
I get less memory free, and eventually I run out (it isn't much each time,
but after e.g. 40 reloads, there aren't many megs left of my initial 64).
I have to debug this now, it will be interesting to see if it is Tomcat
code or my code that have the bug..! ;)

Btw: you can turn on "verbose gc" on the JVM, this is cool:

-verbose:gc
    Report on each garbage collection event.

And then, Yoav, you can se that your objects are killed -when you invoke
gc()-! ;)

Endre.


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