Received: from SOUTH-STATION-ANNEX.MIT.EDU by po7.MIT.EDU (5.61/4.7) id AA28673; Thu, 22 Feb 96 07:38:07 EST Received: from gw4.att.com by MIT.EDU with SMTP id AA25810; Thu, 22 Feb 96 07:37:48 EST To: proven@MIT.EDU Received: by ig4.att.att.com id AA06994; Thu, 22 Feb 96 07:30:46 EST Date: Thu, 22 Feb 96 07:30:46 EST From: uucp@ig4.att.att.com Message-Id: <9602221230.AA06994@ig4.att.att.com> Subject: mail warning Apparently-To: MIT.EDU!proven@ig4.att.att.com We have been unable to contact machine 'pearl' to deliver mail you sent. Our attempts to deliver your mail will continue for 6 more day(s). No further action is required by you. The following mail has not been delivered: pearl!mail erk (Date 02/20) If you wish to kill the job, contact our administrator at postmaster@att.com (att!postmaster) and ask to kill UUCP job pearlJ5d70. Sincerely, postmaster@att.com #################### Data File: #################### From ig4.att.att.com!MIT.EDU!proven Tue Feb 20 15:43:15 1996 remote from att Received: from att!MIT.EDU by ig4.att.att.com id AA22653; Tue, 20 Feb 96 15:43:15 EST Received: by gw4.att.com; Tue Feb 20 15:45:54 EST 1996 Received: from YAZ-PISTACHIO.MIT.EDU by MIT.EDU with SMTP id AA02381; Tue, 20 Feb 96 15:26:14 EST Received: by yaz-pistachio.MIT.EDU (5.57/4.7) id AA11362; Tue, 20 Feb 96 15:26:41 -0500 Message-Id: <9602202026.AA11362@yaz-pistachio.MIT.EDU> To: Samuel Tardieu Cc: pthreads@MIT.EDU Subject: Re: pthreads and fork() In-Reply-To: Your message of "20 Feb 1996 18:34:36 +0100." Date: Tue, 20 Feb 1996 15:26:38 EST From: Christopher Provenzano > >>>>> "Sam" == Samuel Tardieu writes: > > Sam> How is fork() supposed to work with pthreads on Linux ? Is it > Sam> supposed to work or is there anything else which should prevent > Sam> it to do the right job ? > > I'll explain my question : a colleague of mine told me that the > following program: > > ======= > main() > { > if (fork()==0) { > printf("Child\n"); > sleep(5); > printf("End of child\n"); > } else { > printf("Father\n"); > sleep(5); > printf("End of father\n"); > } > } > ======= > > was never returning from the child process on Linux using a dynamic > version of the pthreads library as bundled with the Linux GNAT > distribution. > > Could people with Linux boxes test this simple program for me and send > me a *private* mail (I'll summarize later, don't fill up the mailing > list) with what it did and what pthreads release you used (and > possibly what version of the Linux libc) ? > > Thanks in advance for your cooperation. > > Sam > > PS/ I'm interested even if you use a static version of the pthreads > library. > PPS/ The bug seems to occur only with the Linux version, I just tried > with SunOS and 1.60b4_1 and it works fine. > -- > "La cervelle des petits enfants, ca doit avoir comme un petit gout de noisett > e" > Charles Baudelaire > The sleep() call is deadlocking pthreads because pthreads assumes that you are going to call exec() fairly soon after calling fork() (This is also what POSIX assumes) and has turned off all scheduling operations. Work is under way to make the behavior of fork() more reasonable by tring to eliminate the scheduling deadlock problems but it is adviseable to still call exec() shortly after calling fork() becuase the fork() call will still only create a child process with the current thread running as per the POSIX standard. CAP