Hi Bulat,
On Fri, Aug 7, 2009 at 5:32 PM, Bulat
Ziganshin
Hello Levi,
Friday, August 7, 2009, 6:48:42 PM, you wrote:
1. How can one safely perform a blocking wait on a system call via FFI when compiling with -threaded
i think you should use forkOS to create OS thread dedicated to Haskell thread
Yes, but that wouldn't help me with my problem of getting signal interruptions. Simon Marlow wrote in the haskell-café thread: "The SIGVTALRM signal is delivered to one (random) thread in the program [...]" [1]
and avoid signal interruptions which cause the call to return with EINTR?
don't know, but may be you can retry on this retcode or disable EINTR in one specific OS thread
Yes, currently I use throwErrnoIfMinus1Retry from Foreign.C.Error, but I am not sure if this is the recommended way. Seeing ... rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 rt_sigaction(SIGCHLD, NULL, {SIG_DFL}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 nanosleep({3, 0}, 0xbfad005c) = ? ERESTART_RESTARTBLOCK (To be restarted) --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- sigreturn() = ? (mask now []) ... many times in the output of strace made me slightly uneasy. So right now I have two options which *seem* to work ok. One is to retry on EINTR, and the other to block SIGVTALRM as described in [2]. But am still unsure whether (i) this is correct and recommended, and (ii) there is no better option. Cheers, Levi --- [1] http://www.haskell.org//pipermail/haskell-cafe/2009-August/064971.html [2] http://www.haskell.org//pipermail/haskell-cafe/2009-August/065023.html