problem with pthread.h - child thread's ending locks up main thread

[Ben Lavender <blavender at gmail dot com>]

Hello all, I have a problem.  I have a bug or misconfig that manifests
itself in pthreads.h.

Basically, if a child thread ends, the main thread stops executing. 
The program does not
end, but it doesn't go any further.

I see that a similar problem was posted to this list about 2 weeks
ago, but this is slightly
different, and my example program is not a lab, and does nothing but
show the problem.
I don't see a solution posted to that thread.  

Hopefully, someone can verify this as a bug or show me my
misconfiguration.  Or, of course,
briefly explain to me how I'm misusing pthread_* functions, if that's the case.

Output from cygcheck -s -v -r is attached.


Here is the program executed on a debian sarge box:
ben@hydra:~$ gcc -lpthread threadprob.c
threadprob.c: In function `main':
threadprob.c:15: warning: passing arg 3 of `pthread_create' from incompatible po
inter type
threadprob.c:13: warning: return type of `main' is not `int'
ben@hydra:~$ ./a.out
looping in main
looping in thread func at 1
looping in main
looping in thread func at 2
looping in main
looping in thread func at 3
looping in main
looping in thread func at 4
looping in main
looping in main
looping in main
looping in main
looping in main
looping in main
<ctrl-c>

Here is the program running in my cygwin environment:
Administrator@benlaptop ~/ptp
$ gcc -lpthread threadprob.c
threadprob.c: In function `main':
threadprob.c:15: warning: passing arg 3 of `pthread_create' from incompatible po
inter type
threadprob.c:13: warning: return type of `main' is not `int'

Administrator@benlaptop ~/ptp
$ ./a.exe
looping in main
looping in thread func at 1
looping in main
looping in thread func at 2
looping in main
looping in thread func at 3
looping in main
looping in thread func at 4
looping in main
<ctrl-c after 30 seconds>

Here's the source for threadprob.c:
#include <pthread.h>

void thread_func() {
        int x = 0;
        while (x++ <= 3) {
                printf("looping in thread func at %d\n",x);
                sleep(1);
        }
        pthread_exit(0);
}

void main() {
        pthread_t tid;
        pthread_create(&tid,NULL,thread_func,NULL);
        while (1) {
                printf("looping in main\n");
                sleep(1);
        }
        printf("shouldn't happen\n");
        exit(1);
}

Thanks for your time,
ben

Attachment: cygcheck.out
Description: Binary data

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