diff options
Diffstat (limited to 'Doc/library/signal.rst')
| -rw-r--r-- | Doc/library/signal.rst | 42 |
1 files changed, 21 insertions, 21 deletions
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst index 5033e0e2a9..2db17c5caa 100644 --- a/Doc/library/signal.rst +++ b/Doc/library/signal.rst @@ -39,12 +39,12 @@ rules for working with signals and their handlers: * Some care must be taken if both signals and threads are used in the same program. The fundamental thing to remember in using signals and threads simultaneously is: always perform :func:`signal` operations in the main thread - of execution. Any thread can perform an :func:`alarm`, :func:`getsignal`, - :func:`pause`, :func:`setitimer` or :func:`getitimer`; only the main thread - can set a new signal handler, and the main thread will be the only one to - receive signals (this is enforced by the Python :mod:`signal` module, even - if the underlying thread implementation supports sending signals to - individual threads). This means that signals can't be used as a means of + of execution. Any thread can perform an :func:`alarm`, :func:`getsignal`, + :func:`pause`, :func:`setitimer` or :func:`getitimer`; only the main thread + can set a new signal handler, and the main thread will be the only one to + receive signals (this is enforced by the Python :mod:`signal` module, even + if the underlying thread implementation supports sending signals to + individual threads). This means that signals can't be used as a means of inter-thread communication. Use locks instead. The variables defined in the :mod:`signal` module are: @@ -80,22 +80,22 @@ The variables defined in the :mod:`signal` module are: One more than the number of the highest signal number. -.. data:: ITIMER_REAL +.. data:: ITIMER_REAL Decrements interval timer in real time, and delivers :const:`SIGALRM` upon expiration. -.. data:: ITIMER_VIRTUAL +.. data:: ITIMER_VIRTUAL - Decrements interval timer only when the process is executing, and delivers + Decrements interval timer only when the process is executing, and delivers SIGVTALRM upon expiration. .. data:: ITIMER_PROF - - Decrements interval timer both when the process executes and when the - system is executing on behalf of the process. Coupled with ITIMER_VIRTUAL, - this timer is usually used to profile the time spent by the application + + Decrements interval timer both when the process executes and when the + system is executing on behalf of the process. Coupled with ITIMER_VIRTUAL, + this timer is usually used to profile the time spent by the application in user and kernel space. SIGPROF is delivered upon expiration. @@ -105,7 +105,7 @@ The :mod:`signal` module defines one exception: Raised to signal an error from the underlying :func:`setitimer` or :func:`getitimer` implementation. Expect this error if an invalid - interval timer or a negative time is passed to :func:`setitimer`. + interval timer or a negative time is passed to :func:`setitimer`. This error is a subtype of :exc:`IOError`. @@ -143,21 +143,21 @@ The :mod:`signal` module defines the following functions: .. function:: setitimer(which, seconds[, interval]) - Sets given interval timer (one of :const:`signal.ITIMER_REAL`, + Sets given interval timer (one of :const:`signal.ITIMER_REAL`, :const:`signal.ITIMER_VIRTUAL` or :const:`signal.ITIMER_PROF`) specified - by *which* to fire after *seconds* (float is accepted, different from + by *which* to fire after *seconds* (float is accepted, different from :func:`alarm`) and after that every *interval* seconds. The interval timer specified by *which* can be cleared by setting seconds to zero. When an interval timer fires, a signal is sent to the process. - The signal sent is dependent on the timer being used; - :const:`signal.ITIMER_REAL` will deliver :const:`SIGALRM`, + The signal sent is dependent on the timer being used; + :const:`signal.ITIMER_REAL` will deliver :const:`SIGALRM`, :const:`signal.ITIMER_VIRTUAL` sends :const:`SIGVTALRM`, and :const:`signal.ITIMER_PROF` will deliver :const:`SIGPROF`. The old values are returned as a tuple: (delay, interval). - Attempting to pass an invalid interval timer will cause a + Attempting to pass an invalid interval timer will cause a :exc:`ItimerError`. @@ -186,7 +186,7 @@ The :mod:`signal` module defines the following functions: will be restarted when interrupted by signal *signalnum*, otherwise system calls will be interrupted. Returns nothing. Availability: Unix (see the man page :manpage:`siginterrupt(3)` for further information). - + Note that installing a signal handler with :func:`signal` will reset the restart behaviour to interruptible by implicitly calling :cfunc:`siginterrupt` with a true *flag* value for the given signal. @@ -233,7 +233,7 @@ be sent, and the handler raises an exception. :: signal.alarm(5) # This open() may hang indefinitely - fd = os.open('/dev/ttyS0', os.O_RDWR) + fd = os.open('/dev/ttyS0', os.O_RDWR) signal.alarm(0) # Disable the alarm |