Mercurial > hg
view README @ 27895:2d6a89e79b48
scmutil: support background file closing
Closing files that have been appended to is relatively slow on
Windows/NTFS. This makes several Mercurial operations slower on
Windows.
The workaround to this issue is conceptually simple: use multiple
threads for I/O. Unfortunately, Python doesn't scale well to multiple
threads because of the GIL. And, refactoring our code to use threads
everywhere would be a huge undertaking. So, we decide to tackle this
problem by starting small: establishing a thread pool for closing
files.
This patch establishes a mechanism for closing file handles on separate
threads. The coordinator object is basically a queue of file handles to
operate on and a thread pool consuming from the queue.
When files are opened through the VFS layer, the caller can specify
that delay closing is allowed.
A proxy class for file handles has been added. We must use a proxy
because it isn't possible to modify __class__ on built-in types. This
adds some overhead. But as future patches will show, this overhead
is cancelled out by the benefit of closing file handles on background
threads.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 14 Jan 2016 13:34:59 -0800 |
parents | 4b0fc75f9403 |
children | 76b171209151 |
line wrap: on
line source
Mercurial ========= Mercurial is a fast, easy to use, distributed revision control tool for software developers. Basic install: $ make # see install targets $ make install # do a system-wide install $ hg debuginstall # sanity-check setup $ hg # see help Running without installing: $ make local # build for inplace usage $ ./hg --version # should show the latest version See https://mercurial-scm.org/ for detailed installation instructions, platform-specific notes, and Mercurial user information.