Can't start new thread

While trying to get some multitasking in python via using vast amount of threads, i've hit my head to "can't start new thread" problem.

At first, i thought that max open file limit was the problem, to verify i did a manual checking as seen below.

 In [1]: count = 0
 In [2]: from threading import Thread
 In [3]: def blah():
    ...:     pass
    ...:
 In [4]: while 1:
    ...:     Thread(target=blah).start()
    ...:     count += 1
    ...:
    ...:
 ---------------------------------------------------------------------------
 error                                     Traceback (most recent call last)
 /root/ in ()
 /usr/local/lib/python2.5/threading.pyc in start(self)
     438         _limbo[self] = self
     439         _active_limbo_lock.release()
 --> 440         _start_new_thread(self.__bootstrap, ())
     441         self.__started = True
     442         _sleep(0.000001)    # 1 usec, to let the thread run (Solaris hack)
 error: can't start new thread
 In [5]: print count
 438

438.. ôO'

i was expecting 1024 or so(mostly more than 1024 if running as root) but 438 was way lower than that. It seemed that another problem was going on.

 root@s1 [~]# ulimit -a
 core file size          (blocks, -c) 0
 data seg size           (kbytes, -d) unlimited
 scheduling priority             (-e) 0
 file size               (blocks, -f) unlimited
 pending signals                 (-i) 65536
 max locked memory       (kbytes, -l) 32
 max memory size         (kbytes, -m) unlimited
 open files                      (-n) 65535
 pipe size            (512 bytes, -p) 8
 POSIX message queues     (bytes, -q) 819200
 real-time priority              (-r) 0
 stack size              (kbytes, -s) 10240
 cpu time               (seconds, -t) unlimited
 max user processes              (-u) 65536
 virtual memory          (kbytes, -v) unlimited
 file locks                      (-x) unlimited

stack_size(10mb) seems to be the culprit here. stack_size is basically the maximum memory size a single process can allocate as stack.
10Mbs is much more than needed for my threads, so retrying the manual checking succeeded as expected.

 In [1]: import threading as t
 In [2]: def blah():
    ...:     pass
    ...:
 In [3]: t.stack_size(128*1024)  # 128K would be enough in the real code, so trying it here
 Out[3]: 0
 In [4]: count = 0
 In [5]: while 1:
    ...:     t.Thread(target=blah).start()
    ...:     count +=1
    ...:
    ...:
 ---------------------------------------------------------------------------
 KeyboardInterrupt                         Traceback (most recent call last)
 .........

 KeyboardInterrupt:    # bored waiting :o/

 In [6]: count
 Out[6]: 68348 <------ Yays! 

Now i'm happily enjoying my gazillions of semi-concurrent threads.