checking a thread has started

[Deepak Sarda]

Hi Michael. Thanks for the detailed response..

On 6 Nov 2004 21:26:08 -0700, Michael Fuhr <mfuhr at fuhr.org> wrote:
> You can examine os.environ['GATEWAY_INTERFACE'] to see how your
> script is run: the value should be "CGI/1.1" if you're running
> via CGI and "Python-CGI/1.1" if you're under mod_python.  This
> environment variable probably won't be set if you run the script
> from the command line, so use has_key() or trap KeyError to avoid
> exceptions.
> 

It give 'CGI/1.1' which means no mod_python

> What do you mean "runs as a local user"?  CGI programs usually run
> as whatever user the web server runs as, although it's possible to
> have them run as the script's owner (e.g., by setting up suEXEC).
> 

Yes, it's using the suEXEC mechanism. The script is in my home folder
so it get's executed as my uid/gid.

> 
> That doesn't make sense given the description of StartServers.
> Besides, as I recall, Apache 1.3.27, which you said you were using,
> doesn't even use threads -- each instance of the web server is run
> in a separate process.  Have you tested your hypothesis by altering
> the value of StartServers and checking whether your script behaves
> differently?

I couldn't check this yet as the sys admin is not available. but
something related is there in the mail below.

> > The program _always_ successfully creates and completes  execution of
> > exactly seven new threads leaving the remaining eight requested
> > threads in no man's land!
> 
> How are you determining which threads are starting and which aren't?

Just seeing if the run() is called - with a print. 

> 
> > So there must be some relation between apache and the script. Also, as
> > I said earlier, when run through a shell as the same user - the script
> > works perfectly fine.
> 
> Something's going on but we lack sufficent evidence to say what.
> We haven't seen your code yet -- could you post the smallest possible
> script that demonstrates the problem?
> 
> 

The following script always works for threads less than 8. Increase it
beyond that and it almost always fails. I say almost always because
sometimes it manages to run. But it fails almost 98% of the time
(unscientific observation!). The key thing is the os.system() call.
Without that, everything works fine. Also - if I start the threads
just after creating them - then the success rate become 98% (again -
guess).

#!/usr/bin/python2.2
import sys, os, threading

class Worker(threading.Thread):
    def __init__(self, index):
        self._index = index
        threading.Thread.__init__(self)
        print "Made object", self._index
        sys.stdout.flush()

    def run(self):
        print "Ran thread with index", self._index
        sys.stdout.flush()
        os.system("date")
        sys.stdout.flush()
        Worker.count += 1

if __name__ == '__main__':
    sys.stderr = sys.stdout
    print "Content-type: text/plain\n"
    sys.stdout.flush()

    Worker.count = 0

    tlist = []
    for i in range(10):
        t = Worker(i)
        #t.start()
        tlist.append(t)

    for t in tlist:
       t.start()

    for t in tlist:
        t.join()

    print "Count:", Worker.count


I'll experiment with the other suggestions offered and get back soon.


-- 

Online: http://www.antrix.net/journal/