Mercurial > hg
view contrib/editmergeps.ps1 @ 38732:be4984261611
merge: mark file gets as not thread safe (issue5933)
In default installs, this has the effect of disabling the thread-based
worker on Windows when manifesting files in the working directory. My
measurements have shown that with revlog-based repositories, Mercurial
spends a lot of CPU time in revlog code resolving file data. This ends
up incurring a lot of context switching across threads and slows down
`hg update` operations when going from an empty working directory to
the tip of the repo.
On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs):
before: 487s wall
after: 360s wall (equivalent to worker.enabled=false)
cpus=2: 379s wall
Even with only 2 threads, the thread pool is still slower.
The introduction of the thread-based worker (02b36e860e0b) states that
it resulted in a "~50%" speedup for `hg sparse --enable-profile` and
`hg sparse --disable-profile`. This disagrees with my measurement
above. I theorize a few reasons for this:
1) Removal of files from the working directory is I/O - not CPU - bound
and should benefit from a thread pool (unless I/O is insanely fast
and the GIL release is near instantaneous). So tests like `hg sparse
--enable-profile` may exercise deletion throughput and aren't good
benchmarks for worker tasks that are CPU heavy.
2) The patch was authored by someone at Facebook. The results were
likely measured against a repository using remotefilelog. And I
believe that revision retrieval during working directory updates with
remotefilelog will often use a remote store, thus being I/O and not
CPU bound. This probably resulted in an overstated performance gain.
Since there appears to be a need to enable the thread-based worker with
some stores, I've made the flagging of file gets as thread safe
configurable. I've made it experimental because I don't want to formalize
a boolean flag for this option and because this attribute is best
captured against the store implementation. But we don't have a proper
store API for this yet. I'd rather cross this bridge later.
It is possible there are revlog-based repositories that do benefit from
a thread-based worker. I didn't do very comprehensive testing. If there
are, we may want to devise a more proper algorithm for whether to use
the thread-based worker, including possibly config options to limit the
number of threads to use. But until I see evidence that justifies
complexity, simplicity wins.
Differential Revision: https://phab.mercurial-scm.org/D3963
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 18 Jul 2018 09:49:34 -0700 |
parents | 92bcaef3420b |
children |
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# A simple script for opening merge conflicts in editor # A loose translation of contrib/editmerge to powershell # Please make sure that both editmergeps.bat and editmerge.ps1 are available # via %PATH% and use the following Mercurial settings to enable it # # [ui] # editmergeps # editmergeps.args=$output # editmergeps.check=changed # editmergeps.premerge=keep $file=$args[0] function Get-Lines { Select-String "^<<<<<<" $file | % {"$($_.LineNumber)"} } $ed = $Env:HGEDITOR; if ($ed -eq $nil) { $ed = $Env:VISUAL; } if ($ed -eq $nil) { $ed = $Env:EDITOR; } if ($ed -eq $nil) { $ed = $(hg showconfig ui.editor); } if ($ed -eq $nil) { Write-Error "merge failed - unable to find editor" exit 1 } if (($ed -eq "vim") -or ($ed -eq "emacs") -or ` ($ed -eq "nano") -or ($ed -eq "notepad++")) { $lines = Get-Lines $firstline = if ($lines.Length -gt 0) { $lines[0] } else { $nil } $previousline = $nil; # open the editor to the first conflict until there are no more # or the user stops editing the file while (($firstline -ne $nil) -and ($firstline -ne $previousline)) { if ($ed -eq "notepad++") { $linearg = "-n$firstline" } else { $linearg = "+$firstline" } Start-Process -Wait -NoNewWindow $ed $linearg,$file $previousline = $firstline $lines = Get-Lines $firstline = if ($lines.Length -gt 0) { $lines[0] } else { $nil } } } else { & "$ed" $file } $conflicts=Get-Lines if ($conflicts.Length -ne 0) { Write-Output "merge failed - resolve the conflicts (line $conflicts) then use 'hg resolve --mark'" exit 1 } exit 0