signal module?

[Daniel Nielsen]

On 27/03-03 11.58, Michael Hudson wrote:
> Daniel Nielsen <djn at daimi.au.dk> writes:
> 
> > I'm currently working on some code that uses the signal module... But
> > I doesnt seem to work proberly.
> > 
> > I'm using threads, 
> 
> You are in trouble already.

That I am beginning to realize :)

> > so I'd like ctrl-c to actually terminate the program. If my memory
> > serves me, ctrl-c is SIGINT, so in my code, in the main thread, I
> > write:
> > 
> > signal.signal(signal.SIGINT, gp.handler);
> > 
> > where gp is a module and handler looks like:
> > 
> > def handler(signum, frame):
> >     print "Handling signal: " + signum;
> >     sys.exit(2);
> > 
> > But ctrl-c doesnt do anything!
> > 
> > If I write:
> > signal.signal(signal.SIGINT, signal.SIG_DFL);
> > instead, ctrl-c actually terminates the program...
> > Have I misunderstood something?
> 
> I'd expect this to work, but that it doesn't fails to surprise.  What
> OS (+version, probably) are you on?  Any chance of a complete code
> sample?

Well, I'm running it on the computers that belong to the University
where I study. They are heavily modified RH7.3. I have compiled and
installed python 2.2.2 as a local user.

I seem to have figured out what is going on:

1) When you use the signal module with your OWN handlers (e.g. not
   signal.SIG_DFL or signal.SIG_IGN), it is required that the main
   thread does not exit. The it works like a charm.
2) IF the mainthread exits, then then all handlers defined by signal
   module is ignored. UNLESS it is signal.SIG_DFL, and signal.SIG_IGN.

So, I have solved the problem by not letting the main thread
exit... Seems funny though... 

As for complete source, I have atttached the current version of the
two files. (it is a VERY work in progress, and I'm learning python
along the way). It's supposed to be a genetic programming project, and
I'm in charge of providing a skeleton distributed implementation.

Note, I'm using latest pyro from pyro.sourceforge.net (14. march)

/Daniel

-- 
There are no great men, only great challenges that ordinary men are forced
by circumstances to meet.
		-- Admiral William Halsey
-------------- next part --------------
import threading, Pyro.naming, sys;

#A class, representing a individual
class Myre:
    def __init__(self, name):
        self.name=name;

    def output(self):
        print "Name: " + self.name;


class Population:
    def __init__(self):
        self.pop = [];

    def __len__(self):
        return len(self.pop);

    def append(self, myre):
        if isinstance(myre,Myre):
            self.pop.append(myre);
        else:
            raise TypeError;

    def output(self):
        i = 0;
        for m in self.pop:
            print "Myre " + str(i) + ": "; 
            m.output();
            i += 1;

class Server:
    def __init__(self):
        print "Bringing up server...";
        
    def startNS(self):
        print "Starting the nameserver..."
        self.ns = NSstart();
        #Making the application exit when onlye daemon threads are left
        self.ns.setDaemon(True);
        self.ns.start();
        

class NSstart(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self,name="ns");
    def run(self):
        self.ns = Pyro.naming.NameServerStarter();
        self.ns.start();

#fkt for signal handling
def handler(signum, frame):
    print "Handling signal:", signum;
    sys.exit(2);
-------------- next part --------------
#!/usr/bin/env python

import os, sys, gp, getopt, signal;

CLIENTS=['meltdown','magneto','cyclops','blink'];

def nice():
    #Set this proces nice value... eq. 10 - we are behaving!
    current = os.nice(0);
    inc = 10 - current;
    print "Current niceness is " + str(current) + " adding "+ str(inc);
    os.nice(inc);

def usage():
    print "Usage: "+sys.argv[0]+" -c|--client -s|server";


    
def main():
    nice();
    try:
        opt, args = getopt.getopt(sys.argv[1:],"cs",['client','server']);
    except getopt.GetoptError:
        usage();
        sys.exit(2);


    doClient = False;
    doServer = False;
    for o,a in opt:
        if o in ("-c","--client"):
            #Client time!
            doClient = True;
        if o in ("-s","--server"):
            #Server Time!
            doServer = True;

    if doServer:
        #getting around crtl+c and threads...
        signal.signal(signal.SIGINT, gp.handler);
        server = gp.Server();
        server.startNS();
        print "Creating population...";
        myrerne = gp.Population();
        myrerne.append(gp.Myre("FirkAnt"));
        myrerne.append(gp.Myre("Legions"));
        myrerne.append(gp.Myre("Militant"));
        #ugly hack, not allowing main thread to exit. Should prob'ly sleep
        while True:
            pass;
      

    elif doClient:
        print "Doing client...";

#making script run... could be importet ya know...
if __name__ == "__main__":
    main();