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Date: Wed, 16 Jul 2025 23:40:18 +0900
To: cygwin AT cygwin DOT com, newlib AT sourceware DOT org
Subject: Re: doxygen hangs when many call graphs are generated.
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From: Takashi Yano via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>
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On Wed, 16 Jul 2025 22:45:32 +0900
Takashi Yano via Cygwin <cygwin AT cygwin DOT com> wrote:
> On Wed, 16 Jul 2025 21:36:04 +0900
> Takashi Yano via Cygwin <cygwin AT cygwin DOT com> wrote:
> > On Wed, 16 Jul 2025 21:13:59 +0900
> > Takashi Yano via Cygwin <cygwin AT cygwin DOT com> wrote:
> > 
> > > On Tue, 17 Jun 2025 21:46:47 +0900
> > > Takashi Yano wrote:
> > > > I encountered a problem of doxygen when many call graphs are generated.
> > > > 
> > > > How to reproduce:
> > > > 1) Make a empty directory.
> > > > 2) Place two files (Doxyfile, x.c) attached in the directory.
> > > > 3) Run doxygen in the directory.
> > > > 
> > > > It seems that this is a bug of cygwin1.dll and the cause is
> > > > a deadlock in newlib/libc/stdio/findfp.c:__fp_lock_all().
> 
> A simple reproducer is as follows.
> 
> #include <unistd.h>
> #include <stdio.h>
> #include <pthread.h>
> #include <sys/wait.h>
> 
> void *func(void *arg)
> {
> 	while (1) {
> 		FILE *f = fopen("/usr/bin/cygwin1.dll", "r"); /* Open something */
> 		fclose(f);
> 	}
> 	return NULL;
> }
> 
> int main()
> {
> 	pthread_t th;
> 	pthread_create(&th, NULL, func, NULL);
> 	int cnt = 0;
> 	while (1) {
> 		if (fork() == 0) {
> 			return 0;
> 		} else {
> 			wait(NULL);
> 			printf("Done %d\n", cnt++);
> 		}
> 	}
> }

I have submitted a patch for this issue to newlib mailing list.

-- 
Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>

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