I've got a situation in which I'd like to hand one end of a pipe to
another process. First, in case you ask why, a spawner process is
created early before many modules are imported. That spawner process is
responsible for creating new processes and giving a proxy to the parent
process.
(h1-1 <-- Pipe() --> h1-2)
|------------------------> child1
|(s1 < Pipe() > s2)
parent -> spawner -> |--> child2
|(h2-1) <-- Pipe() --> (h2-2)
|----------------------|
|------------------------> child3
(h3-1 <-- Pipe() --> h3-2)
When I try to pass Connection h1-1 to the parent using Connection s1, I
get an error:
TypeError: Required argument 'handle' (pos 1) not found
This error is from unpickling the Connection h1-1. You can duplicate
the error like this:
pickled_connection = pickle.dumps(h1-1, 2)
pickle.loads(pickled_connection) # raises the same error
Looking at the pickle docs, I wonder if this could be resolved by adding
a __getnewargs__ method to _multiprocessing.Connection. But even if
that would work I couldn't do it now since it's an extension module.
I've thought about trying to recreate the Connection. Looks like it
should be possible with Connection.fileno(). The Unix portion looks
easy, but the win32 portion does not.
So if it's possible, what's the best way to pass a Connection to another
process?
Randall
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