Python: What is the default handling of SIGTERM?

python signals sigterm
meteoritepanama picture meteoritepanama · Mar 29, 2012 · Viewed 9.8k times · Source

What does Python do under the covers by default if it receives a SIGTERM but there is no signal handler registered for it?

Answer

stochastic picture stochastic · Jan 25, 2017

Building on the answer of Thomas Wouters, python does not register a handler for the SIGTERM signal. We can see this by doing:

In[23]: signal.SIG_DFL == signal.signal(signal.SIGTERM,signal.SIG_DFL)
Out[23]: True

That means that the system will take the default action. On linux, the default action (according to the signal man page) for a SIGTERM is to terminate the process.

Terminating a process means that:

  • the process will simply not be allocated any more time slices during which it can execute code.

    • This means that it will not raise an exception, or call the code in try: finally: blocks, or the __exit__ method of context managers. It will not do those things because that particular python interpreter will never get the chance to execute another instruction.

  • The process's memory and other resources (open files, network sockets, etc...) will be released back to the rest of the system.

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