From patchwork Wed May 28 05:05:21 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [5, of, 5] dirstate.status: assign members one by one instead of unpacking the tuple From: Siddharth Agarwal X-Patchwork-Id: 4879 Message-Id: <124fd417846a9105b62b.1401253521@dev1738.prn1.facebook.com> To: Date: Tue, 27 May 2014 22:05:21 -0700 # HG changeset patch # User Siddharth Agarwal # Date 1401249736 25200 # Tue May 27 21:02:16 2014 -0700 # Node ID 124fd417846a9105b62b067c2d21990a2e44467e # Parent 9ed8b0fa79cfa5f220930c92ac79b93f6d6bd8ee dirstate.status: assign members one by one instead of unpacking the tuple The CPython UNPACK_SEQUENCE opcode has fast paths when the value to be unpacked is a tuple or a list, but falls back to creating a full-fledged iterator in general. That is much slower than simply accessing and storing the tuple members one by one. With this patch, hg status and hg diff regain their previous speed. The following tests are run against a working copy with over 270,000 files. Here, 'before' means without this or the previous patch applied. Note that in this case `hg perfstatus` isn't representative since it doesn't take dirstate parsing time into account. $ time hg status # best of 5 before: 2.03s user 1.25s system 99% cpu 3.290 total after: 2.01s user 1.25s system 99% cpu 3.261 total $ time hg diff # best of 5 before: 1.32s user 0.78s system 99% cpu 2.105 total after: 1.27s user 0.79s system 99% cpu 2.066 total diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py --- a/mercurial/dirstate.py +++ b/mercurial/dirstate.py @@ -823,7 +823,11 @@ uadd(fn) continue - state, mode, size, time = dmap[fn] + t = dmap[fn] + state = t[0] + mode = t[1] + size = t[2] + time = t[3] if not st and state in "nma": dadd(fn)