[bug?] 2nd printf output gets gobbled up when 1st used in a thread

furrylogical furrylogical@gmail.com
Tue Jan 1 21:16:00 GMT 2013


Hello everyone,

Cygwin seems to behave strangely when `printf` is used in threads: if
the first `printf` encountered occurs in another thread, then the
first `printf` that occurs in the main function will vanish into thin
air.  The following fragment illustrates this:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

void *func(void *arg)
{
    printf("thread_printf\n");
    return NULL;
}

int main(int argc, char **argv)
{
    pthread_t thread;
    pthread_create(&thread, NULL, func, NULL);
    pthread_join(thread, NULL);
    printf("main_printf1\n");           /* This line never gets printed */
    printf("main_printf2\n");
    return 0;
}

When compiled with `gcc` with no options, the output is:
  thread_printf
  main_printf2

I'm not familiar with the Cygwin codebase.  If someone can point me in
the right direction, I might be able to figure out what is causing
this issue.

I appreciate the if someone can help me figure this out, though I
understand it's not exactly a critical issue.  Thanks all.
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