maximum number of threads

[Paul Sijben]

All thanks for all the input! This was very informative.

Looks like I indeed need stackless as my code benefits from being
concurrently designed.

Paul

Jean-Paul Calderone wrote:
> On Wed, 10 Jan 2007 12:11:59 -0200, Felipe Almeida Lessa
> <felipe.lessa at gmail.com> wrote:
>> On 1/10/07, Laurent Pointal <laurent.pointal at limsi.fr> wrote:
>>> This is a system configurable limit (up to a maximum).
>>>
>>> See ulimit man pages.
>>>
>>> test
>>>
>>>         ulimit -a
>>>
>>> to see what are the current limits, and try with
>>>
>>>         ulimit -u 2000
>>>
>>> to modify the maximum number of user process (AFAIK each thread use a
>>> process entry on Linux)
>>
>> I don't think it's only this.
> 
> Indeed you are correct.  The actual limit you are hitting is the size
> of your address space.  Each thread is allocated 8MB of stack.  382
> threads consumes about 3GB of address space.  Even though most of this
> memory isn't actually allocated, the address space is still used up.  So,
> when you try to create the 383rd thread, the kernel can't find anyplace
> to put its stack.  So you can't create it.
> 
> Try reducing your stack size or reducing the number of threads you create.
> There's really actually almost no good reason to have this many threads,
> even though it's possible.
> 
>    exarkun at charm:~$ python Desktop/test.py
>    50
>    100
>    150
>    200
>    250
>    300
>    350
>    Exception raised: can't start new thread
>       Biggest number of threads: 382
>    exarkun at charm:~$ ulimit -Ss 4096
>    exarkun at charm:~$ python Desktop/test.py
>    50
>    100
>    150
>    200
>    250
>    300
>    350
>    400
>    450
>    500
>    550
>    600
>    650
>    700
>    750
>    Exception raised: can't start new thread
>       Biggest number of threads: 764
>    exarkun at charm:~$
>    Jean-Paul