Takashi Yano wrote:
On Wed, 12 Jan 2022 07:41:41 +0100
Marco Atzeri wrote:
On 12.01.2022 07:27, Jay K wrote:
Ok, here is a small demonstration of the problem.
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
unsigned __stdcall thread(void* p)
{
unsigned i;
for (i = 0; i < 100; ++i)
system("./a.exe");
return 0;
}
int main()
{
unsigned i;
HANDLE threads[100] = {0};
FILE* f = fopen("a.c", "w");
fprintf(f, "int main() { return 0; }\n");
fclose(f);
so you are mixing Cygwin and Windows calls ?
That is looking for trouble.
Or it is a tentative to produce a test case ?
I found that the same happens even with pthread rather than
win32 thread functions.
#include <stdlib.h>
#include <pthread.h>
void *thread(void *p)
{
system("true");
return NULL;
}
int main()
{
int i;
pthread_t threads[2];
for (i = 0; i < 2; i++)
pthread_create(&threads[i], NULL, thread, NULL);
for (i = 0; i < 2; i++)
pthread_join(threads[i], NULL);
return 0;
}
Executing above code results in hang with message:
0 [waitproc] a 786 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
POSIX does not require system() to be thread-safe. On Cygwin, it isn't. When I
ran into this a while back, I implemented an application wrapper around system()
to serialize calls. It's tricky because you want to serialize just the mechanism
of system(), not the programs that the multiple system()s call.
..mark
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