Python 3.2+sysfunction

sys.setswitchinterval()

interpreter

Sets the thread switch interval in seconds — how often the thread holding the GIL yields it to others. Rarely needed: for experiments and fine tuning.

Syntax

sys.setswitchinterval(interval)

A smaller interval makes I/O threads more responsive but adds switching overhead; a larger one does the opposite. It cannot speed up computation with threads. The value is process-wide, and zero or negative numbers raise ValueError. When you change it in tests, restore the old value or neighbouring tests will suffer.

Examples

import sys
old = sys.getswitchinterval()
sys.setswitchinterval(0.001)
print(sys.getswitchinterval())  # → 0.001
sys.setswitchinterval(old)
try:
    sys.setswitchinterval(0)
except ValueError as e:
    print(e)  # → switch interval must be strictly positive

See also

Common errors

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