all Python 3Linux · macOSsignalfunction

signal.setitimer()

timers

Starts an interval timer with microsecond resolution, one-shot or repeating. Unix only (Linux, macOS).

Syntax

signal.setitimer(which, seconds, interval=0.0)

ITIMER_REAL sends SIGALRM and shares it with alarm — they disrupt each other. ITIMER_VIRTUAL and ITIMER_PROF count CPU time, not wall time: they stand still during sleep. A non-zero interval repeats the signal forever, so clearing the timer with setitimer(which, 0) is mandatory. A negative time raises signal.ItimerError, a subclass of OSError.

Examples

import signal, time
ticks = []
old = signal.signal(signal.SIGALRM, lambda s, f: ticks.append(s))
signal.setitimer(signal.ITIMER_REAL, 0.01, 0.01)  # каждые 10 мс
try:
    while len(ticks) < 3:
        time.sleep(0.005)
finally:
    signal.setitimer(signal.ITIMER_REAL, 0)  # снять обязательно
    signal.signal(signal.SIGALRM, old)
print(len(ticks))  # → 3

import signal
try:
    signal.setitimer(signal.ITIMER_REAL, -1)
except OSError as e:
    print(isinstance(e, signal.ItimerError))  # → True

See also

Common errors

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