Date: Thu, 08 Feb 2007 06:51:04 -0800 From: Garrett Cooper <youshi10@u.washington.edu> To: freebsd-hackers@freebsd.org Subject: Re: Trying to join an already exited pthread Message-ID: <45CB38D8.1000706@u.washington.edu> In-Reply-To: <87D4B047-DC72-427B-863F-A082C3A4E5CD@u.washington.edu> References: <Pine.LNX.4.43.0702071314560.22034@hymn08.u.washington.edu> <eqdhl2$1tmb$1@wattres.Watt.COM> <87D4B047-DC72-427B-863F-A082C3A4E5CD@u.washington.edu>
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Garrett Cooper wrote: > On Feb 7, 2007, at 1:51 PM, Steve Watt wrote: > >> In <Pine.LNX.4.43.0702071314560.22034@hymn08.u.washington.edu>, >> <youshi10@u.washington.edu> wrote: >>> Just wondering: >>> >>> If I was to try and join a pthread that already exited, would there >>> be an error >>> message output and/or errno set to an error value, or would a system >>> hang? >> >> Was the thread created with detach state set PTHREAD_CREATE_DETACHED or >> PTHREAD_CREATE_JOINABLE? If it was PTHREAD_CREATE_JOINABLE, has the >> thread already been joined? >> >> You should be able to join a thread that was created joinable, only once. >> If you join it again, or join a thread that was created detached, the >> results are unspecified in POSIX. There is an error status that may >> be returned, but it may do other bad things to your system. >> >> Note that pthread_join doesn't set errno; it returns an error value >> directly. I would never expect the system to hang, though the >> application >> might. If your application is hanging, make sure that you're not trying >> to call pthread_join from within a signal handler. >> >>> It this variable on Unix OSes? >> >> That the results are unspecified? No. What "unspecified" means? >> Absolutely. >> --Steve Watt KD6GGD PP-ASEL-IA ICBM: 121W 56' 57.5" / 37N >> 20' 15.3" >> Internet: steve @ Watt.COM Whois: SW32-ARIN >> Free time? There's no such thing. It just comes in varying prices... > > I asked this because I was short on time and so was the person who > asked me earlier. I'm going to try giving the pthread exit and join a > shot just to see whether or not this is true or not and then I'll report > my results to the list. > Thanks for the insight though--hopefully my results will yield a > solid positive or negative to this being a problem. > -Garrett Under Suse Linux there were absolutely no errors when I tried to do this. I'll post a code snippet later. -Garrett
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