On Fri, 19 Aug 2005, Christophe Yayon wrote: > Hi all > > You should know about freebsd and nagios 2.0b threads issues (100% cpu > use by a forked process, lost check result, some pause of nagios main > process in certains obscursives conditions...). > > Some Nagios developpers says that the problem is in FreeBSD and some > other says that the problem is in nagios pthreads implementation, here a > resume of our discussions : > From > > http://www.opengroup.org/onlinepubs/009695399/functions/pthread_atfork.html > > "It is suggested that programs that use fork() call an exec function > very soon afterwards in the child process, thus resetting all states. In > the meantime, only a short list of async-signal-safe library routines > are promised to be available." > > Note *suggested*. This is a recommendation to protect against a shoddy > pthread-implementation. The thread specifications rule that only the > thread calling fork() is duplicated, which initially leads to the > recommendation (other threads holding locks aren't around to release > them in the new execution context).
They choose to quote a weak reference to the actual requirement. The standard says (in the fork() section): A process shall be created with a single thread. If a multi-threaded process calls fork(), the new process shall contain a replica of the calling thread and its entire address space, possibly including the states of mutexes and other resources. Consequently, to avoid errors, the child process may only execute async-signal-safe operations until such time as one of the exec functions is called. Fork handlers may be established by means of the pthread_atfork() function in order to maintain application invariants across fork() calls. -- DE _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
