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merge: mark file gets as not thread safe (issue5933)...
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
Gregory Szorc -
r38755:be498426 default
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WiX installer source files
==========================

The files in this folder are used by the thg-winbuild [1] package
building architecture to create a Mercurial MSI installer. These files
are versioned within the Mercurial source tree because the WXS files
must kept up to date with distribution changes within their branch. In
other words, the default branch WXS files are expected to diverge from
the stable branch WXS files. Storing them within the same repository is
the only sane way to keep the source tree and the installer in sync.

The MSI installer builder uses only the mercurial.ini file from the
contrib/win32 folder, the contents of which have been historically used
to create an InnoSetup based installer. The rest of the files there are
ignored.

The MSI packages built by thg-winbuild require elevated (admin)
privileges to be installed due to the installation of MSVC CRT libraries
under the C:\WINDOWS\WinSxS folder. Thus the InnoSetup installers may
still be useful to some users.

To build your own MSI packages, clone the thg-winbuild [1] repository
and follow the README.txt [2] instructions closely. There are fewer
prerequisites for a WiX [3] installer than an InnoSetup installer, but
they are more specific.

Direct questions or comments to Steve Borho <steve@borho.org>

[1] http://bitbucket.org/tortoisehg/thg-winbuild
[2] http://bitbucket.org/tortoisehg/thg-winbuild/src/tip/README.txt
[3] http://wix.sourceforge.net/