Mercurial > hg
view tests/test-treediscovery.t @ 26623:5a95fe44121d
clonebundles: support for seeding clones from pre-generated bundles
Cloning can be an expensive operation for servers because the server
generates a bundle from existing repository data at request time. For
a large repository like mozilla-central, this consumes 4+ minutes
of CPU time on the server. It also results in significant network
utilization. Multiplied by hundreds or even thousands of clients and
the ensuing load can result in difficulties scaling the Mercurial server.
Despite generation of bundles being deterministic until the next
changeset is added, the generation of bundles to service a clone request
is not cached. Each clone thus performs redundant work. This is
wasteful.
This patch introduces the "clonebundles" extension and related
client-side functionality to help alleviate this deficiency. The
client-side feature is behind an experimental flag and is not enabled by
default.
It works as follows:
1) Server operator generates a bundle and makes it available on a
server (likely HTTP).
2) Server operator defines the URL of a bundle file in a
.hg/clonebundles.manifest file.
3) Client `hg clone`ing sees the server is advertising bundle URLs.
4) Client fetches and applies the advertised bundle.
5) Client performs equivalent of `hg pull` to fetch changes made since
the bundle was created.
Essentially, the server performs the expensive work of generating a
bundle once and all subsequent clones fetch a static file from
somewhere. Scaling static file serving is a much more manageable
problem than scaling a Python application like Mercurial. Assuming your
repository grows less than 1% per day, the end result is 99+% of CPU
and network load from clones is eliminated, allowing Mercurial servers
to scale more easily. Serving static files also means data can be
transferred to clients as fast as they can consume it, rather than as
fast as servers can generate it. This makes clones faster.
Mozilla has implemented similar functionality of this patch on
hg.mozilla.org using a custom extension. We are hosting bundle files in
Amazon S3 and CloudFront (a CDN) and have successfully offloaded
>1 TB/day in data transfer from hg.mozilla.org, freeing up significant
bandwidth and CPU resources. The positive impact has been stellar and
I believe it has proved its value to be included in Mercurial core. I
feel it is important for the client-side support to be enabled in core
by default because it means that clients will get faster, more reliable
clones and will enable server operators to reduce load without
requiring any client-side configuration changes (assuming clients are
up to date, of course).
The scope of this feature is narrowly and specifically tailored to
cloning, despite "serve pulls from pre-generated bundles" being a valid
and useful feature. I would eventually like for Mercurial servers to
support transferring *all* repository data via statically hosted files.
You could imagine a server that siphons all pushed data to bundle files
and instructs clients to apply a stream of bundles to reconstruct all
repository data. This feature, while useful and powerful, is
significantly more work to implement because it requires the server
component have awareness of discovery and a mapping of which changesets
are in which files. Full, clone bundles, by contrast, are much simpler.
The wire protocol command is named "clonebundles" instead of something
more generic like "staticbundles" to leave the door open for a new, more
powerful and more generic server-side component with minimal backwards
compatibility implications. The name "bundleclone" is used by Mozilla's
extension and would cause problems since there are subtle differences
in Mozilla's extension.
Mozilla's experience with this idea has taught us that some form of
"content negotiation" is required. Not all clients will support all
bundle formats or even URLs (advanced TLS requirements, etc). To ensure
the highest uptake possible, a server needs to advertise multiple
versions of bundles and clients need to be able to choose the most
appropriate from that list one. The "attributes" in each
server-advertised entry facilitate this filtering and sorting. Their
use will become apparent in subsequent patches.
Initial inspiration and credit for the idea of cloning from static files
belongs to Augie Fackler and his "lookaside clone" extension proof of
concept.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 09 Oct 2015 11:22:01 -0700 |
parents | 8c14f87bd0ae |
children | b74ca9ace65e |
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#require killdaemons Tests discovery against servers without getbundle support: $ CAP="getbundle bundle2" $ . "$TESTDIR/notcapable" $ cat >> $HGRCPATH <<EOF > [ui] > logtemplate="{rev} {node|short}: {desc} {branches}\n" > EOF Setup HTTP server control: $ remote=http://localhost:$HGPORT/ $ export remote $ tstart() { > echo '[web]' > $1/.hg/hgrc > echo 'push_ssl = false' >> $1/.hg/hgrc > echo 'allow_push = *' >> $1/.hg/hgrc > hg serve -R $1 -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log > cat hg.pid >> $DAEMON_PIDS > } $ tstop() { > killdaemons.py > [ "$1" ] && cut -d' ' -f6- access.log && cat errors.log > rm access.log errors.log > } Both are empty: $ hg init empty1 $ hg init empty2 $ tstart empty2 $ hg incoming -R empty1 $remote comparing with http://localhost:$HGPORT/ no changes found [1] $ hg outgoing -R empty1 $remote comparing with http://localhost:$HGPORT/ no changes found [1] $ hg pull -R empty1 $remote pulling from http://localhost:$HGPORT/ no changes found $ hg push -R empty1 $remote pushing to http://localhost:$HGPORT/ no changes found [1] $ tstop Base repo: $ hg init main $ cd main $ hg debugbuilddag -mo '+2:tbase @name1 +3:thead1 <tbase @name2 +4:thead2 @both /thead1 +2:tmaintip' $ hg log -G o 11 a19bfa7e7328: r11 both | o 10 8b6bad1512e1: r10 both | o 9 025829e08038: r9 both |\ | o 8 d8f638ac69e9: r8 name2 | | | o 7 b6b4d315a2ac: r7 name2 | | | o 6 6c6f5d5f3c11: r6 name2 | | | o 5 70314b29987d: r5 name2 | | o | 4 e71dbbc70e03: r4 name1 | | o | 3 2c8d5d5ec612: r3 name1 | | o | 2 a7892891da29: r2 name1 |/ o 1 0019a3b924fd: r1 | o 0 d57206cc072a: r0 $ cd .. $ tstart main Full clone: $ hg clone main full updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd full $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes no changes found $ hg push $remote pushing to http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. Local is empty: $ cd empty1 $ hg incoming $remote comparing with http://localhost:$HGPORT/ 0 d57206cc072a: r0 1 0019a3b924fd: r1 2 a7892891da29: r2 name1 3 2c8d5d5ec612: r3 name1 4 e71dbbc70e03: r4 name1 5 70314b29987d: r5 name2 6 6c6f5d5f3c11: r6 name2 7 b6b4d315a2ac: r7 name2 8 d8f638ac69e9: r8 name2 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ hg outgoing $remote comparing with http://localhost:$HGPORT/ no changes found [1] $ hg push $remote pushing to http://localhost:$HGPORT/ no changes found [1] $ hg pull $remote pulling from http://localhost:$HGPORT/ requesting all changes adding changesets adding manifests adding file changes added 12 changesets with 24 changes to 2 files (run 'hg update' to get a working copy) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. Local is subset: $ hg clone main subset --rev name2 ; cd subset adding changesets adding manifests adding file changes added 6 changesets with 12 changes to 2 files updating to branch name2 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 6 a7892891da29: r2 name1 7 2c8d5d5ec612: r3 name1 8 e71dbbc70e03: r4 name1 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg push $remote pushing to http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 6 changesets with 12 changes to 2 files (run 'hg update' to get a working copy) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop Remote is empty: $ tstart empty2 $ cd main $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 0 d57206cc072a: r0 1 0019a3b924fd: r1 2 a7892891da29: r2 name1 3 2c8d5d5ec612: r3 name1 4 e71dbbc70e03: r4 name1 5 70314b29987d: r5 name2 6 6c6f5d5f3c11: r6 name2 7 b6b4d315a2ac: r7 name2 8 d8f638ac69e9: r8 name2 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes no changes found $ hg push $remote pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 12 changesets with 24 changes to 2 files $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop Local is superset: $ hg clone main subset2 --rev name2 adding changesets adding manifests adding file changes added 6 changesets with 12 changes to 2 files updating to branch name2 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ tstart subset2 $ cd main $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 2 a7892891da29: r2 name1 3 2c8d5d5ec612: r3 name1 4 e71dbbc70e03: r4 name1 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes no changes found $ hg push $remote pushing to http://localhost:$HGPORT/ searching for changes abort: push creates new remote branches: both, name1! (use 'hg push --new-branch' to create new remote branches) [255] $ hg push $remote --new-branch pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 6 changesets with 12 changes to 2 files $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop Partial pull: $ tstart main $ hg clone $remote partial --rev name2 adding changesets adding manifests adding file changes added 6 changesets with 12 changes to 2 files updating to branch name2 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd partial $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 6 a7892891da29: r2 name1 7 2c8d5d5ec612: r3 name1 8 e71dbbc70e03: r4 name1 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ hg incoming $remote --rev name1 comparing with http://localhost:$HGPORT/ searching for changes 6 a7892891da29: r2 name1 7 2c8d5d5ec612: r3 name1 8 e71dbbc70e03: r4 name1 $ hg pull $remote --rev name1 pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 3 changesets with 6 changes to 2 files (+1 heads) (run 'hg heads' to see heads) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 9 025829e08038: r9 both 10 8b6bad1512e1: r10 both 11 a19bfa7e7328: r11 both $ cd .. $ tstop Both have new stuff in new named branches: $ hg clone main repo1a --rev name1 -q $ hg clone repo1a repo1b -q $ hg clone main repo2a --rev name2 -q $ hg clone repo2a repo2b -q $ tstart repo1a $ cd repo2a $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 6 a7892891da29: r2 name1 7 2c8d5d5ec612: r3 name1 8 e71dbbc70e03: r4 name1 $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 2 70314b29987d: r5 name2 3 6c6f5d5f3c11: r6 name2 4 b6b4d315a2ac: r7 name2 5 d8f638ac69e9: r8 name2 $ hg push $remote --new-branch pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 4 changesets with 8 changes to 2 files (+1 heads) $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 3 changesets with 6 changes to 2 files (+1 heads) (run 'hg heads' to see heads) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop $ tstart repo1b $ cd repo2b $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 6 a7892891da29: r2 name1 7 2c8d5d5ec612: r3 name1 8 e71dbbc70e03: r4 name1 $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 2 70314b29987d: r5 name2 3 6c6f5d5f3c11: r6 name2 4 b6b4d315a2ac: r7 name2 5 d8f638ac69e9: r8 name2 $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 3 changesets with 6 changes to 2 files (+1 heads) (run 'hg heads' to see heads) $ hg push $remote --new-branch pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 4 changesets with 8 changes to 2 files (+1 heads) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop Both have new stuff in existing named branches: $ rm -r repo1a repo1b repo2a repo2b $ hg clone main repo1a --rev 3 --rev 8 -q $ hg clone repo1a repo1b -q $ hg clone main repo2a --rev 4 --rev 7 -q $ hg clone repo2a repo2b -q $ tstart repo1a $ cd repo2a $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 8 d8f638ac69e9: r8 name2 $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 4 e71dbbc70e03: r4 name1 $ hg push $remote --new-branch pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 1 changesets with 2 changes to 2 files $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 1 changesets with 2 changes to 2 files (run 'hg update' to get a working copy) $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop $ tstart repo1b $ cd repo2b $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes 8 d8f638ac69e9: r8 name2 $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes 4 e71dbbc70e03: r4 name1 $ hg pull $remote pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 1 changesets with 2 changes to 2 files (run 'hg update' to get a working copy) $ hg push $remote --new-branch pushing to http://localhost:$HGPORT/ searching for changes remote: adding changesets remote: adding manifests remote: adding file changes remote: added 1 changesets with 2 changes to 2 files $ hg incoming $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ hg outgoing $remote comparing with http://localhost:$HGPORT/ searching for changes no changes found [1] $ cd .. $ tstop show "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=heads HTTP/1.1" 200 - "GET /?cmd=branches HTTP/1.1" 200 - x-hgarg-1:nodes=d8f638ac69e9ae8dea4f09f11d696546a912d961 "GET /?cmd=between HTTP/1.1" 200 - x-hgarg-1:pairs=d8f638ac69e9ae8dea4f09f11d696546a912d961-d57206cc072a18317c1e381fb60aa31bd3401785 "GET /?cmd=changegroupsubset HTTP/1.1" 200 - x-hgarg-1:bases=d8f638ac69e9ae8dea4f09f11d696546a912d961&heads=d8f638ac69e9ae8dea4f09f11d696546a912d961 "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=heads HTTP/1.1" 200 - "GET /?cmd=branches HTTP/1.1" 200 - x-hgarg-1:nodes=d8f638ac69e9ae8dea4f09f11d696546a912d961 "GET /?cmd=between HTTP/1.1" 200 - x-hgarg-1:pairs=d8f638ac69e9ae8dea4f09f11d696546a912d961-d57206cc072a18317c1e381fb60aa31bd3401785 "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks "GET /?cmd=heads HTTP/1.1" 200 - "GET /?cmd=branches HTTP/1.1" 200 - x-hgarg-1:nodes=d8f638ac69e9ae8dea4f09f11d696546a912d961 "GET /?cmd=between HTTP/1.1" 200 - x-hgarg-1:pairs=d8f638ac69e9ae8dea4f09f11d696546a912d961-d57206cc072a18317c1e381fb60aa31bd3401785 "GET /?cmd=changegroupsubset HTTP/1.1" 200 - x-hgarg-1:bases=d8f638ac69e9ae8dea4f09f11d696546a912d961&heads=d8f638ac69e9ae8dea4f09f11d696546a912d961 "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=heads HTTP/1.1" 200 - "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks "GET /?cmd=branchmap HTTP/1.1" 200 - "GET /?cmd=branchmap HTTP/1.1" 200 - "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks "POST /?cmd=unbundle HTTP/1.1" 200 - x-hgarg-1:heads=686173686564+1827a5bb63e602382eb89dd58f2ac9f3b007ad91 "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=heads HTTP/1.1" 200 - "GET /?cmd=capabilities HTTP/1.1" 200 - "GET /?cmd=heads HTTP/1.1" 200 -