Maybe I overstated the "make sure" a bit but....
"cannot create native thread" but hey wait....You have pleanty of heap
right? DOH, stack generally doesn't come out of the JAVA-side heap. So
threads use BOTH heap and the "C side" of the Java process. Meaning the
formula is something like:
Max # threads ~ (Max RSS Size - (Heap Size + Java Overhead + other C
stuff like file handles and NIO stuff + Thread Local vars)) /
StackPerThread
Which means that you are probably okay for small apps. Large apps that
start > say around 2000 threads and use a lot of TLVs you're going to
hit "cannot create native thread"
512k is a pretty big stack! Many server side apps aren't very recursive
or method deep (calls come out of the stack obviously). So if I see
"cannot create native thread" and maybe an OOME and yet I've got pleanty
of heap...its probably stack vs process size. Most server apps are safe
with a 128k stack which means I get a factor of 4x more threads minus
entropic factors and part of the Thread object of course does come out
of the Java heap.
Anyhow, I never get a chance to do formal benching so I'm not sure what
the exact numbers are with all equal factors, I usually only have time
to solve the critical problems then move to the next place. Note that
one is about Sun's VM and the -XX:ThreadStackSize is a Solaris thing
(-Xss only makes it bigger but it ignores it being smaller), but it
seems recent versions of the Linux VM allow it too (but -Xss seems to
let you make it smaller anyhow on Linux). Does that make sense?
-Andy
Michael Czeiszperger wrote:
On Jul 12, 2005, at 1:19 PM, [EMAIL PROTECTED] wrote:
5. Make sure you reduce -XX:+ThreadStackSize and -Xss so that you do
not get 512k-1M stack per thread (generally excessive, but these are
the defaults for -server on 32 and 64bit respectively)
Many thanks for the detailed suggestions. Could you please elaborate
on the effects of this?
________________________________________________________________________
_________
Run, run, run, as fast as you can. You can't catch me, I'm the stinky
cheese man!
-- michael at czeiszperger dot org, Chapel Hill, NC
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