Announcing MozillaBuild 3.1.1 Release

Gregory Szorc gps at
Mon Dec 4 23:34:43 UTC 2017

On Tue, Nov 28, 2017 at 5:03 PM, Xidorn Quan <me at> wrote:

> On Wed, Nov 29, 2017, at 10:55 AM, Ryan VanderMeulen wrote:
> * The fsmonitor extension was re-disabled due to significant performance
> regressions for some common operations caused by watchman excessively
> polling the filesystem.
> <>
> <>
> If you're already using version 3.1 without issue, you probably don't need
> to pick up this release. You may want to consider disabling fsmonitor in
> the mean time, however. You can do that by making the change below to
> <mozilla-build>/python/mercurial.ini:
> It isn't clear to me what performance issue it has.
> From the bug, I can see the issue gps raised on GitHub:
> So my question would be, does it affect building Firefox in subdirectory
> of working directory? If it does, then it sounds very serious and people
> should probably disable it. If it doesn't, maybe it isn't a too big deal,
> since I don't think most developers want to create tons of files frequently.

I noticed the problem just running `hg pull` and `hg update` operations.
(pull because of changes to the .hg directory and update because of working
directory changes.) I was seeing a ~10x slowdown for large operations.

Fortunately, the issue is now fixed in upstream watchman. So watchman
should make a return in the next MozillaBuild. If you can't wait, the link
to download the latest Watchman for Windows build can be found at
Extract that into your MozillaBuild install and revert to enable Watchman.
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