view CONTRIBUTORS @ 29787:80df04266a16

hgweb: profile HTTP requests

Currently, running `hg serve --profile` doesn't yield anything useful:
when the process is terminated the profiling output displays results
from the main thread, which typically spends most of its time in
select.select(). Furthermore, it has no meaningful results from
mercurial.* modules because the threads serving HTTP requests don't
actually get profiled.

This patch teaches the hgweb wsgi applications to profile individual
requests. If profiling is enabled, the profiler kicks in after
HTTP/WSGI environment processing but before Mercurial's main request
processing.

The profile results are printed to the configured profiling output.
If running `hg serve` from a shell, they will be printed to stderr,
just before the HTTP request line is logged. If profiling to a file,
we only write a single profile to the file because the file is not
opened in append mode. We could add support for appending to files
in a future patch if someone wants it.

Per request profiling doesn't work with the statprof profiler because
internally that profiler collects samples from the thread that
*initially* requested profiling be enabled. I have plans to address
this by vendoring Facebook's customized statprof and then improving
it.

[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]

Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>