[Pyobjc-dev] Threading [Was: Re: Achieving 1.0....]

[Bill B. <bb...@co...>]

On Tuesday, October 29, 2002, at 04:17 PM, Jack Jansen wrote:
> Something else you may want to try though, if this is needed for 
> PyObjC, is to let the thread terminate. The comments in NSThread.h 
> lead me to believe that once you've made the transition to a 
> multithreaded program there's no going back. If that's indeed the case 
> then letting the thread terminate isn't a problem.

I wrote a little hunk of code to verify the behavior and you are 
correct-- a program can only become multithreaded, but will never 
revert to single threaded.   However, given that there is both a 
NSWillBecomeMultiThreadedNotification and a 
NSDidBecomeSingleThreadedNotification notification, it would seem that 
Apple intends to someday support the transition from multi->single 
threaded.

As such -- I would recommend leaving in the deadlocked thread.

NSDidBecomeSingleThreadedNotification is currently documented as "Not 
Implemented.".

(To test this case, create a new "foundation tool" project and replace 
the contents of main.m with the code shown below.

// --- start of code
#import <Foundation/Foundation.h>

@interface NSObject (TheVoid)
+ (void) intoTheVoid: aNothing;
@end
@implementation NSObject (TheVoid)
+ (void) intoTheVoid: aNothing;
{
/*  NSLock *l = [[NSLock alloc] init];
   [l lock];
   [l lock];*/
}

- (void) receiveNotification: aNotification
{
   NSLog(@"Recieved %@", aNotification);
}

- (void) timerFired: anObject
{
   NSLog(@"Timer fired.");
}
@end

int main (int argc, const char * argv[]) {
   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

   [[NSNotificationCenter defaultCenter]
     addObserver: [NSObject class]
        selector: @selector(receiveNotification:)
            name: nil
          object: nil];

   [NSThread detachNewThreadSelector:@selector(intoTheVoid:) 
toTarget:[NSObject class] withObject: nil];
   [NSTimer scheduledTimerWithTimeInterval: 5.0
                                    target: [NSObject class]
                                  selector: @selector(timerFired:)
                                  userInfo: nil
                                   repeats: NO];
   [[NSRunLoop currentRunLoop] runUntilDate: [NSDate distantFuture]];

   [pool release];
   return 0;
}
// ------- end of code

2002-10-29 18:19:29.512 threadtest[14834] Recieved 
NSConcreteNotification 5a740 {name = 
NSWillBecomeMultiThreadedNotification}
2002-10-29 18:19:29.558 threadtest[14834] Recieved 
NSConcreteNotification 5a740 {name = _NSThreadDidStartNotification}
2002-10-29 18:19:29.629 threadtest[14834] Recieved 
NSConcreteNotification 5cec0 {name = NSThreadWillExitNotification; 
object = <NSThread: 0x5ce80>{num = 2, threadDictionary =
(null)
}}
2002-10-29 18:19:34.559 threadtest[14834] Timer fired.

threadtest has exited with status 0.


b.bum
We gladly feast on those who would subdue us.