Gunter Henriksen wrote:
If you don't want to use a 3rd party module you could
use the multiprocessing module
That is definitely good for when I have a tree of
processes which are all Python applications. I use
it for that. But I am looking for something where
the Python application can interact conveniently
with an arbitrary external application. Using a
socket/pipe and shared memory is convenient, but
not feasible when system call overhead matters.
Linux doesn't do interprocess communication very well.
The options are pipes (clunky), sockets (not too bad, but
excessive overhead), System V IPC (nobody uses
that) and shared memory (unsafe).
If you want to see IPC right, what you really need is
the QNX microkernel, and its messaging system. I've pumped
uncompressed video through the QNX messaging system and had
only 2% of the CPU devoted to message overhead. The basic
primitives are MsgSend, MsgReceive, and MsgReply, which do
about what you'd expect and do it very fast. Linux lacks
this.
If you're using CPython, don't worry about socket overhead.
CPython is so slow you'll never notice it.
John Nagle
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