Mercurial > hg-stable
view tests/test-obsolete-changeset-exchange.t @ 26379:39d643252b9f
revlog: use existing file handle when reading during _addrevision
_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.
If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.
After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.
On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:
Call Before After Delta
write 827,639 673,390 -154,249
open 700,103 684,089 -16,014
read 74,489 74,489 0
fstat 493,924 461,896 -32,028
close 249,131 233,117 -16,014
stat 242,001 242,001 0
lstat 18,676 18,676 0
lseek 20,268 20,268 0
ioctl 14,652 13,173 -1,479
TOTAL 3,180,758 2,930,679 -250,079
It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().
Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.
On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.
Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 27 Sep 2015 16:08:18 -0700 |
parents | fab9dda0f2a3 |
children | f20533623833 |
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Test changesets filtering during exchanges (some tests are still in test-obsolete.t) $ cat >> $HGRCPATH << EOF > [experimental] > evolution=createmarkers > EOF Push does not corrupt remote ---------------------------- Create a DAG where a changeset reuses a revision from a file first used in an extinct changeset. $ hg init local $ cd local $ echo 'base' > base $ hg commit -Am base adding base $ echo 'A' > A $ hg commit -Am A adding A $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg revert -ar 1 adding A $ hg commit -Am "A'" created new head $ hg log -G --template='{desc} {node}' @ A' f89bcc95eba5174b1ccc3e33a82e84c96e8338ee | | o A 9d73aac1b2ed7d53835eaeec212ed41ea47da53a |/ o base d20a80d4def38df63a4b330b7fb688f3d4cae1e3 $ hg debugobsolete 9d73aac1b2ed7d53835eaeec212ed41ea47da53a f89bcc95eba5174b1ccc3e33a82e84c96e8338ee Push it. The bundle should not refer to the extinct changeset. $ hg init ../other $ hg push ../other pushing to ../other searching for changes adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 2 files $ hg -R ../other verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 2 changesets, 2 total revisions Adding a changeset going extinct locally ------------------------------------------ Pull a changeset that will immediatly goes extinct (because you already have a marker to obsolete him) (test resolution of issue3788) $ hg phase --draft --force f89bcc95eba5 $ hg phase -R ../other --draft --force f89bcc95eba5 $ hg commit --amend -m "A''" $ hg --hidden --config extensions.mq= strip --no-backup f89bcc95eba5 $ hg pull ../other pulling from ../other searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 1 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) check that bundle is not affected $ hg bundle --hidden --rev f89bcc95eba5 --base "f89bcc95eba5^" ../f89bcc95eba5.hg 1 changesets found $ hg --hidden --config extensions.mq= strip --no-backup f89bcc95eba5 $ hg unbundle ../f89bcc95eba5.hg adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 1 files (+1 heads) (run 'hg heads' to see heads)