From: Joel Reymont <[EMAIL PROTECTED]>
To: "Branimir Maksimovic" <[EMAIL PROTECTED]>
CC: haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Re: syscall, sigpause and EINTR on Mac OSX
Date: Sun, 11 Dec 2005 18:25:47 +0000
Understood. But I'm printing things in the signal handler to show that it
was triggered. And I trigger it when ^C is pressed (well, one more
signal):
initSnippets :: IO ()
initSnippets =
do initSSL
installHandler sigPIPE Ignore Nothing
flip mapM_ [sigTERM, sigINT] $ \sig -> do
installHandler sig (handler sig) Nothing
where handler sig = Catch $
do trace_ $ "Signal " ++ show sig + + "
caught."
trace_ "Broadcasting Quit..."
broadcast (ForcedQuit :: Event ())
This way I know what the signal was that triggered the handler and I can
tell that it was triggered. The deadlock is somewhere else because the
handler is not being tripped.
After seeing this only I can tell that for example in C++ one can't cout
clog cerr
or post some event via synchronized event queue or condition variable
from signal handler.
All of that would result in ghosts and goblins in program.
Actually one can't do much at all in signal handlers in multithreaded
environment, cause they don;t like each other.
If you wan;t to trap ^C then I advise that you give up signal handlers
and dedicate one thread to read keyboard events then post
those keyboard events like you do from signal handler.
That is ignore all signals, but fatal ones in which case you will just
abort program (perhaps try some cleanup, if at all possible from
signal handler)
Hope this helps.
Greetings, Bane.
The issue of the signal handler being tripped by a phantom ^C (signal 2)
is another issue entirely.
On Dec 11, 2005, at 6:10 PM, Branimir Maksimovic wrote:
Though I frorgot to add that deadlock can be caused by signal somewhere
else
(eg other thread) if signal handler eg locks mutex internally or calls
some
other non asynchronous safe functions like locking functions.
This is likely scenario, if you doubt at signal handlers but I don;t know
the details
. Deadlocks can be caused by other things, not neccessarily signals.
--
http://wagerlabs.com/
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