Mercurial > hg
changeset 35787:a84dbc87dae9
exchange: send bundle2 stream clones uncompressed
Stream clones don't compress well. And compression undermines
a point of stream clones which is to trade significant CPU
reductions by increasing size.
Building upon our introduction of metadata to communicate bundle
information back to callers of exchange.getbundlechunks(), we add
an attribute to the bundler that communicates whether the bundle is
best left uncompressed. We return this attribute as part of the bundle
metadata. And the wire protocol honors it when determining whether
to compress the wire protocol response.
The added test demonstrates that the raw result from the wire
protocol is not compressed. It also demonstrates that the server
will serve stream responses when the feature isn't enabled. We'll
address that in another commit.
The effect of this change is that server-side CPU usage for bundle2
stream clones is significantly reduced by removing zstd compression.
For the mozilla-unified repository:
before: 37.69 user 8.01 system
after: 27.38 user 7.34 system
Assuming things are CPU bound, that ~10s reduction would translate to
faster clones on the client. zstd can decompress at >1 GB/s. So the
overhead from decompression on the client is small in the grand scheme
of things. But if zlib compression were being used, the overhead would
be much greater.
Differential Revision: https://phab.mercurial-scm.org/D1926
| author | Gregory Szorc <gregory.szorc@gmail.com> |
|---|---|
| date | Mon, 22 Jan 2018 12:12:29 -0800 |
| parents | 8144f1b07e21 |
| children | b116a66bcc44 |
| files | mercurial/bundle2.py mercurial/exchange.py mercurial/wireproto.py tests/test-clone-uncompressed.t |
| diffstat | 4 files changed, 42 insertions(+), 3 deletions(-) [+] |
line wrap: on
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--- a/mercurial/bundle2.py Mon Jan 22 12:38:04 2018 -0800 +++ b/mercurial/bundle2.py Mon Jan 22 12:12:29 2018 -0800 @@ -599,6 +599,10 @@ self.capabilities = dict(capabilities) self._compengine = util.compengines.forbundletype('UN') self._compopts = None + # If compression is being handled by a consumer of the raw + # data (e.g. the wire protocol), unsetting this flag tells + # consumers that the bundle is best left uncompressed. + self.prefercompressed = True def setcompression(self, alg, compopts=None): """setup core part compression to <alg>"""
--- a/mercurial/exchange.py Mon Jan 22 12:38:04 2018 -0800 +++ b/mercurial/exchange.py Mon Jan 22 12:12:29 2018 -0800 @@ -1763,6 +1763,8 @@ func(bundler, repo, source, bundlecaps=bundlecaps, b2caps=b2caps, **pycompat.strkwargs(kwargs)) + info['prefercompressed'] = bundler.prefercompressed + return info, bundler.getchunks() @getbundle2partsgenerator('stream') @@ -1770,6 +1772,12 @@ b2caps=None, heads=None, common=None, **kwargs): if not kwargs.get('stream', False): return + + # Stream clones don't compress well. And compression undermines a + # goal of stream clones, which is to be fast. Communicate the desire + # to avoid compression to consumers of the bundle. + bundler.prefercompressed = False + filecount, bytecount, it = streamclone.generatev2(repo) requirements = ' '.join(sorted(repo.requirements)) part = bundler.newpart('stream', data=it)
--- a/mercurial/wireproto.py Mon Jan 22 12:38:04 2018 -0800 +++ b/mercurial/wireproto.py Mon Jan 22 12:12:29 2018 -0800 @@ -862,7 +862,7 @@ raise error.Abort(bundle2requiredmain, hint=bundle2requiredhint) - preferuncompressed = False + prefercompressed = True try: if repo.ui.configbool('server', 'disablefullbundle'): @@ -879,6 +879,7 @@ info, chunks = exchange.getbundlechunks(repo, 'serve', **pycompat.strkwargs(opts)) + prefercompressed = info.get('prefercompressed', True) except error.Abort as exc: # cleanly forward Abort error to the client if not exchange.bundle2requested(opts.get('bundlecaps')): @@ -894,9 +895,9 @@ bundler.addpart(bundle2.bundlepart('error:abort', manargs, advargs)) chunks = bundler.getchunks() - preferuncompressed = True + prefercompressed = False - return streamres(gen=chunks, prefer_uncompressed=preferuncompressed) + return streamres(gen=chunks, prefer_uncompressed=not prefercompressed) @wireprotocommand('heads') def heads(repo, proto):
--- a/tests/test-clone-uncompressed.t Mon Jan 22 12:38:04 2018 -0800 +++ b/tests/test-clone-uncompressed.t Mon Jan 22 12:12:29 2018 -0800 @@ -47,6 +47,32 @@ rbc-revs-v1 #endif +getbundle requests with stream=1 are uncompressed + + $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle' content-type --bodyfile body --hgproto '0.1 0.2 comp=zlib,none' --requestheader "x-hgarg-1=bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=0&common=0000000000000000000000000000000000000000&heads=c17445101a72edac06facd130d14808dfbd5c7c2&stream=1" + 200 Script output follows + content-type: application/mercurial-0.2 + + + $ f --size --hex --bytes 256 body + body: size=112328 + 0000: 04 6e 6f 6e 65 48 47 32 30 00 00 00 00 00 00 00 |.noneHG20.......| + 0010: 72 06 53 54 52 45 41 4d 00 00 00 00 04 00 09 05 |r.STREAM........| + 0020: 09 04 0c 2d 07 02 62 79 74 65 63 6f 75 6e 74 39 |...-..bytecount9| + 0030: 38 37 35 38 66 69 6c 65 63 6f 75 6e 74 31 30 33 |8758filecount103| + 0040: 30 72 65 71 75 69 72 65 6d 65 6e 74 73 64 6f 74 |0requirementsdot| + 0050: 65 6e 63 6f 64 65 20 66 6e 63 61 63 68 65 20 67 |encode fncache g| + 0060: 65 6e 65 72 61 6c 64 65 6c 74 61 20 72 65 76 6c |eneraldelta revl| + 0070: 6f 67 76 31 20 73 74 6f 72 65 76 65 72 73 69 6f |ogv1 storeversio| + 0080: 6e 76 32 00 00 10 00 73 08 42 64 61 74 61 2f 30 |nv2....s.Bdata/0| + 0090: 2e 69 00 03 00 01 00 00 00 00 00 00 00 02 00 00 |.i..............| + 00a0: 00 01 00 00 00 00 00 00 00 01 ff ff ff ff ff ff |................| + 00b0: ff ff 80 29 63 a0 49 d3 23 87 bf ce fe 56 67 92 |...)c.I.#....Vg.| + 00c0: 67 2c 69 d1 ec 39 00 00 00 00 00 00 00 00 00 00 |g,i..9..........| + 00d0: 00 00 75 30 73 08 42 64 61 74 61 2f 31 2e 69 00 |..u0s.Bdata/1.i.| + 00e0: 03 00 01 00 00 00 00 00 00 00 02 00 00 00 01 00 |................| + 00f0: 00 00 00 00 00 00 01 ff ff ff ff ff ff ff ff f9 |................| + --uncompressed is an alias to --stream #if stream-legacy