global interpreter lock not working as it should

[brueckd at tbye.com]

On 1 Aug 2002, Armin Steinhoff wrote:

> > Not all built-in functions that may block waiting for I/O allow other threads >to run. (The most popular ones (time.sleep(), file.read(),
> >select.select()) work as expected.) 
> 
> Yes ... only the most 'popular' ones are working

So which ones aren't working for you? Please post some code.

> (because there is only ONE
> system thread (or process) spent for the interpreter)

Really? Consider:

import threading, time
def f():
  while 1:
    time.sleep(1)

for i in range(3):
  threading.Thread(target=f).start()

Now from my Linux cmd line:

> ps -aux | grep python
dave     16839  0.0  0.7  9272 1868 pts/4    S    11:07   0:00 python
dave     16840  0.0  0.7  9272 1868 pts/4    S    11:07   0:00 python
dave     16841  0.0  0.7  9272 1868 pts/4    S    11:07   0:00 python
dave     16842  0.0  0.7  9272 1868 pts/4    S    11:07   0:00 python

On Linux this is especially easy to see because you basically get one 
process per thread, but on other platforms (e.g. Windows) C-level calls to 
get the number of threads by the process return the correct number (at 
least 4 in this case).