Date: Wed, 11 Jan 2012 12:21:18 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: sem(4) lockup in python? Message-ID: <jejrbe$or8$1@dough.gmane.org>
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The lang/python27 port can optionally be built with the support for POSIX semaphores - i.e. sem(4). This option is labeled as experimental so it may be that the code is simply incorrect. I've tried it and get frequent hangs with the python process in the "usem" state. The kernel stack is as follows and looks reasonable: # procstat -kk 19008 PID TID COMM TDNAME KSTACK 19008 101605 python - mi_switch+0x174 sleepq_catch_signals+0x2f4 sleepq_wait_sig+0x16 _sleep+0x269 do_sem_wait+0xa19 __umtx_op_sem_wait+0x51 amd64_syscall+0x450 Xfast_syscall+0xf7 The process doesn't react to SIGINT or SIGTERM but fortunately reacts to SIGKILL. This could be an error in Python code but OTOH this code is not FreeBSD-specific so it's unlikely.
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