[Python-Dev] Request for inclusion in 2.5.2 (5-for-1) (original) (raw)

Guido van Rossum guido at python.org
Fri Nov 2 14:57:49 CET 2007

On 10/31/07, Mike Klaas <mike.klaas at gmail.com> wrote:

Issue http://bugs.python.org/issue1663329 details an annoyance in the subprocess module that has affected several users, including me. Essentially, closing hundreds of thousands of file descriptors by round-tripping through the python exception machinery is very slow, taking hundreds of milliseconds and at times many seconds. The proposed fix is to write this loop in c. The c function is but a handful of lines long. I purposefully kept the implementation trivial so that it will work on all unix variants (there is another issue that contains a super-duper optimization for AIX, and other possibilities exist for Solaris, but the simple fix yields a ten-fold speedup everywhere but windows, so I didn't think that it was worth the complexity).

Though technically relating only to performance, I consider this a bug-fix candidate as mysterious multi-second delays when launching a subprocess end up making the functionality of closefds unusable on some platform configurations (namely, those with high MAXFD set). It would be great to see this is 2.5.2. Understanding that issue evaluation takes significant effort, I've done some evaluation/triage on other open tickets:

Thanks for doing these!

Since people are already jumping on those bugs but nobody has voiced an opinion on your own patch, let me say that I think it's a good patch, and I want it in 2.6, but I'm reluctant to add it to 2.5.2 as it goes well beyond a bugfix (adding a new C API and all that).

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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