Charles-François Natali <[email protected]> added the comment:
In the common case, I don't think that the os.waitpid(0, 0) is the hot spot,
but rather this:
for child in self.active_children:
os.waitpid(child, os.WNOHANG)
It's called every time, and it's O(number of active children).
os.waitpid(0, 0) is only called when max_children (40) is reached. Also, I'm
not sure why it's called without WNOHANG, because that means that we will block
until active_children falls below max_children. That's an arbitrary limit,
especially since it's not documented.
I've written a first draft patch using process group, that removes
active_children and max_children.
The only slightly tricky part is the call to setpgid from the child and from
the parent, to avoid a race where the child could try to join a stale PGID.
Note that I assume that setpgid is available on every Unix, since according to
http://pubs.opengroup.org/onlinepubs/007908799/xsh/setpgid.html , it's "Derived
from the POSIX.1-1988 standard".
Also, according to buildbots' configure logs, it's available everywhere.
----------
keywords: +patch
Added file: http://bugs.python.org/file22124/ss_wait_group.diff
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