Re: Max number of threads with NPTL

Hi

I have successfuly folowed your advise. After rekompiling the kernel so that I now can address 4G of memory, change the max #processes plus changed the thread stacksize i now can create more than 12 000 threads (which is pretty cool i thing), the limit must now be the 4G addressspace limit. I guess the next step is to buy i 64 bit platform...

Many thanks

/Daniel


On Wed, 04 Feb 2004 09:56:57 -0800
Hui Huang <[email protected]> wrote:

> Nathan Bryant wrote:
> > Daniel Malmkvist wrote:
> > 
> >> To my supprise i could not have more then ~3500 threads at the same time.
> >> I got a OutOfMemoryException, but there was plenty of system memory left
> >> (the JVM only ha about 10% of system physical memory).
> >>  
> >>
> > Address space might be a limiting factor in a 32-bit machine. Assuming a 
> > 3gig/1gig VM split, you have less than a megabyte per thread stack at 
> > 3500 threads, even assuming there is no other memory overhead, and there 
> > is a lot of other overhead... Did you try using the Thread constructor 
> > that specifies a stack size? Try specifying a single page - 4K.
> > 
> > You might also need to increase the maximum size of the Java heap. (Or 
> > decrease it to make room for more stack?) I have found that it can't 
> > grow beyond 1.5gig on x86.
> > 
> > If you are allocating the default stack size which is probably fairly 
> > large, 
> 
> Default stack size is 512k. You need 3500 * 512k = 1750M address space
> for 3500 threads. Try -Xss96k. Also check your limit on max #processes
> (ulimit -u), you can't create more threads than that limit either.
> 
> regards,
> -hui
> 
>           the system won't appear to be using the memory because the stack
> > pages won't have corresponding physical pages allocated by the VM until 
> > they are used - the stacks grow down. But they are still allocated 
> > virtual address space within the process.
> > 
> > 
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> 
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