[Python-Dev] Status of thread cancellation (original) (raw)

Jon Ribbens jon+python-dev at unequivocal.co.uk
Mon Mar 19 16:28:33 CET 2007

Nick Maclaren <nmm1 at cus.cam.ac.uk> wrote:

Sockets, terminals etc. are stateful devices, and killing a process can leave them in a very unclean state. It is one of the most common causes of unkillable processes (the process can't go until its files do, and the socket is jammed).

Can you elaborate on this? You can get zombie entries in the process table if nobody's called 'wait()' on them, and you can (extremely rarely) get unkillable process in 'disk-wait' state (usually due to hardware failure or a kernel bug, I suspect), but I've never heard of a process on a Unix-like system being unkillable due to something to do with sockets (or any other kind of file descriptor for that matter). How could a socket be 'jammed'? What does that even mean?

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