SIGSEGV problem

[Martin Pala]

Hi,

during tests occasionaly one of monit threads receives SIGSEGV. It 
happens in the case, that the monitored process is not running.

the path to the SIGSEGV is as follows:

1.) we're waiting for process to start in main thread after spawning 
process start method:
...
thread is status= pthread_create(&thread, NULL, wait_start, s);
...

2.) in new thread (in wait_start) we detach and looking for process to 
start or timeout:
...
if(is_process_running(s))
break;
...

3.) the thread crashed rigth after first call of is_process_running(s) 
-> get_pid(s->path) -> exist_file(char *file) -> stat(file, &buf) - see 
strace output for complete trace:
...
3788 stat64("XE^^G^H/run/slapd.pid", <unfinished ...>
...


As you can see, it seems that the pidfile path pointer points to strange 
place.

This problem happens very occasionaly (cca 5% of test attempts failed on 
this error - others were OK).

I tried to include some debug tags to trace it - something like 
fprintf(stderr, "mark1"); etc., but as soon as i did it, i was not able 
to replicate the problem at all. I tied it many times again with and 
without these tags and the result was the same - with tags it worked 
well, without tags it failed => probably there is some race condition, 
maybe outside monit (in libs).

Any ideas?

Martin

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