Git 减慢了 Emacs 的速度——如何解决这个问题? [英] Git slows down Emacs to Death - How to Fix this?
问题描述
打开文件(通过输入Ctrl-x f，AKA Find File)或在文件上输入 模式)，在具有 f>Dired.git 子目录的工作目录中非常缓慢.
Opening a file (either by typing Ctrl-x f, AKA Find File) or by typing f on that file in Dired mode), is painfully slow in working directories that have a .git subdirectory.
即使是最简单的文件(50 行，大部分是注释)也可能需要 8 秒才能打开.
Even the simplest file (50 lines with mostly comments) could take up to 8 seconds to open.
在不由 Git 管理的不同目录中的同一个文件会立即打开.
The same file, in a different directory not managed by Git, opens in a jiffy, immediately.
为什么会发生这种情况，如何在不禁用 vc 模式的情况下解决此问题??(因为我使用 Emacs 的主要原因之一是它的 M-x ediff-revision)
Why is this happening and how can I fix this without disabling vc-mode? (since one of the main reasons I use Emacs is its M-x ediff-revision)
更新 1:感谢@sanityinc 在下面的回答，我运行了 ELP Profiling，这是我收到的(对于一个非常小的文件，69 行，其中 59 行是简单的评论):>
UPDATE 1: Thanks to @sanityinc's answer below, I ran ELP Profiling and this is what I received (for a very small file, 69 lines, 59 of which are plain comments):
Function Name Call Count Elapsed Time Average Time
------------- ---------- ------------ ------------
vc-call-backend 11 23.023 2.093
vc-find-file-hook 1 8.757 8.757
vc-mode-line 1 7.812 7.812
vc-default-mode-line-string 1 7.345 7.345
vc-state-refresh 1 6.921 6.921
vc-state 1 6.921 6.921
vc-default-state-heuristic 1 6.921 6.921
vc-registered 1 0.945 0.945
vc-backend 1 0.945 0.945
vc-git-registered 1 0.912 0.912
vc-working-revision 1 0.4240000000 0.4240000000
vc-find-root 4 0.0990000000 0.0247500000
vconcat 623 0.0220000000 3.53...e-005
vc-bzr-registered 1 0.016 0.016
vc-check-master-templates 2 0.014 0.007
vc-default-registered 2 0.014 0.007
vc-rcs-registered 1 0.008 0.008
vc-sccs-registered 1 0.006 0.006
vc-svn-registered 1 0.002 0.002
vc-cvs-registered 1 0.001 0.001
vc-sccs-search-project-dir 1 0.0 0.0
vc-kill-buffer-hook 6 0.0 0.0
vc-find-backend-function 11 0.0 0.0
vc-default-find-file-hook 1 0.0 0.0
vc-possible-master 6 0.0 0.0
vc-file-clearprops 1 0.0 0.0
vc-file-setprop 3 0.0 0.0
vc-file-getprop 5 0.0 0.0
vc-make-backend-sym 15 0.0 0.0
这是很好的信息，但我不是 Emacs/elisp 专家，那么我该怎么做呢?
This is great information but I am not an Emacs/elisp expert, so how where do I go from here?
更新 2: 在将这个问题搁置一段时间后，我发现了这篇很棒的博文:Cygwin 缓慢启动:发现了罪魁祸首！ 这实质上表明在后台启动 bash 完成.我很快实现了它并重新运行了 ELP 分析测试:
UPDATE 2: After putting this problem on the back burner for a while, I came across this great blog post: Cygwin slow start up: the culprit discovered! which essentially suggests starting bash completion in the background. I quickly implemented it and re-ran the ELP profiling test:
vc-call-backend 11 14.489 1.317
vc-find-file-hook 1 5.488 5.488
vc-mode-line 1 5.118 5.118
vc-default-mode-line-string 1 4.719 4.719
vc-state-refresh 1 4.282 4.282
vc-state 1 4.282 4.282
vc-default-state-heuristic 1 4.282 4.282
vc-working-revision 1 0.437 0.437
vc-registered 1 0.37 0.37
vc-backend 1 0.37 0.37
vc-git-registered 1 0.34 0.34
vc-find-root 4 0.088 0.022
vc-bzr-registered 1 0.015 0.015
vc-check-master-templates 2 0.013 0.0065
vc-default-registered 2 0.013 0.0065
vc-rcs-registered 1 0.007 0.007
vc-sccs-registered 1 0.006 0.006
vc-cvs-registered 1 0.001 0.001
vconcat 623 0.001 1.60...e-006
vc-svn-registered 1 0.001 0.001
vc-sccs-search-project-dir 1 0.0 0.0
vc-kill-buffer-hook 6 0.0 0.0
vc-find-backend-function 11 0.0 0.0
vc-default-find-file-hook 1 0.0 0.0
vc-possible-master 6 0.0 0.0
vc-file-clearprops 1 0.0 0.0
vc-file-setprop 3 0.0 0.0
vc-file-getprop 5 0.0 0.0
vc-make-backend-sym 15 0.0 0.0
很高兴看到 vc-call-backend 从 23 秒下降到 14 秒，但这仍然是不可接受的(找到一个 CVS 控制的文件只需要不到一秒钟的时间！).
It's great to see vc-call-backend going down from 23 seconds to 14 seconds, but this is still unacceptable (finding a CVS-controlled file takes less than a split-second!).
更新 3: 无法解开谜团，我通过升级到最新的 cygwin (1.7.9-1) 来试试运气.那没有帮助.
UPDATE 3: Unable to solve the mystery, I tried my luck by upgrading to the latest cygwin (1.7.9-1). That didn't help.
所以，我决定尝试将沙箱(连同它的 .git 子目录)从 Samba 共享移动到本地存储(C:UsersWinWinDocuments).然后我重新运行了 ELP 分析测试:
So, I decided to try moving the sandbox (along with its .git subdirectory) from the Samba share to local storage (C:UsersWinWinDocuments). I then re-ran the ELP profiling test:
vc-call-backend 11 2.082 0.1892727272
vc-find-file-hook 1 0.897 0.897
vc-git--call 7 0.8929999999 0.1275714285
vc-git-mode-line-string 1 0.78 0.78
vc-mode-line 1 0.78 0.78
vc-default-mode-line-string 1 0.655 0.655
vc-git--out-ok 5 0.6519999999 0.1304
vc-git-state 1 0.53 0.53
vc-state-refresh 1 0.53 0.53
vc-state 1 0.53 0.53
vc-default-state-heuristic 1 0.53 0.53
vc-git-working-revision 2 0.25 0.125
vc-git-registered 2 0.2239999999 0.1119999999
vc-git--run-command-string 1 0.18 0.18
vc-working-revision 1 0.125 0.125
vc-registered 1 0.1169999999 0.1169999999
vc-backend 2 0.1169999999 0.0584999999
vc-git--empty-db-p 1 0.11 0.11
vc-find-root 3 0.003 0.001
vc-git-root 2 0.002 0.001
vc-check-master-templates 2 0.001 0.0005
vc-sccs-registered 1 0.001 0.001
vc-default-registered 2 0.001 0.0005
vc-bzr-registered 1 0.001 0.001
vc-rcs-registered 1 0.0 0.0
vc-sccs-search-project-dir 1 0.0 0.0
vc-kill-buffer-hook 5 0.0 0.0
vc-default-find-file-hook 1 0.0 0.0
vc-possible-master 6 0.0 0.0
vc-cvs-registered 1 0.0 0.0
vc-file-clearprops 1 0.0 0.0
vc-file-setprop 3 0.0 0.0
vc-file-getprop 5 0.0 0.0
vc-svn-registered 1 0.0 0.0
vc-make-backend-sym 2 0.0 0.0
哇！这将 vc-call-backend 从 14 秒降低到 2 秒.这很棒但并不美妙，因为使用 Emacs/CVS 我能够在 不到 35 毫秒 内访问一个文件——在沙箱最初所在的同一个 Samba 共享上:
Wow! That lowered vc-call-backend from 14 seconds to 2 seconds. This is great but not wonderful, because with Emacs/CVS I am able to visit a file in less than 35ms -- on the same Samba share where the sandbox originally resides:
vc-call-backend 5 0.031 0.0062
vc-find-file-hook 1 0.031 0.031
vc-registered 1 0.031 0.031
vc-backend 1 0.031 0.031
vc-rcs-registered 1 0.016 0.016
vc-check-master-templates 1 0.016 0.016
vc-default-registered 1 0.016 0.016
vc-insert-file 1 0.015 0.015
vc-cvs-get-entries 1 0.015 0.015
vc-cvs-registered 1 0.015 0.015
vc-cvs-state-heuristic 1 0.0 0.0
vc-cvs-parse-sticky-tag 1 0.0 0.0
vc-kill-buffer-hook 1 0.0 0.0
vc-find-backend-function 1 0.0 0.0
vc-cvs-parse-entry 1 0.0 0.0
vc-mode-line 1 0.0 0.0
vc-default-find-file-hook 1 0.0 0.0
vc-possible-master 3 0.0 0.0
vc-cvs-mode-line-string 1 0.0 0.0
vc-default-mode-line-string 1 0.0 0.0
vc-state-refresh 1 0.0 0.0
vc-working-revision 1 0.0 0.0
vc-state 1 0.0 0.0
vc-file-clearprops 1 0.0 0.0
vc-file-setprop 5 0.0 0.0
vc-file-getprop 7 0.0 0.0
vc-make-backend-sym 2 0.0 0.0
这提出了两个问题:
- git+cygwin 的组合使得它对网速?
- 我怎样才能让 git 减少到 50 毫秒以内?毕竟是通话快速版本控制系统"
使用 msysgit 1.7.8 时更新:
vc-call-backend 11 0.626 0.0569090909
vc-find-file-hook 1 0.281 0.281
vc-mode-line 1 0.2189999999 0.2189999999
vc-default-mode-line-string 1 0.1879999999 0.1879999999
vc-state-refresh 1 0.157 0.157
vc-state 1 0.157 0.157
vc-default-state-heuristic 1 0.157 0.157
vc-registered 1 0.062 0.062
vc-backend 1 0.062 0.062
vc-git-registered 1 0.062 0.062
vc-working-revision 1 0.0310000000 0.0310000000
vc-rcs-registered 1 0.0 0.0
vc-sccs-search-project-dir 1 0.0 0.0
vc-kill-buffer-hook 6 0.0 0.0
vc-find-backend-function 11 0.0 0.0
vc-default-find-file-hook 1 0.0 0.0
vc-possible-master 6 0.0 0.0
vc-check-master-templates 2 0.0 0.0
vc-cvs-registered 1 0.0 0.0
vc-sccs-registered 1 0.0 0.0
vc-file-clearprops 1 0.0 0.0
vconcat 623 0.0 0.0
vc-default-registered 2 0.0 0.0
vc-file-setprop 3 0.0 0.0
vc-find-root 4 0.0 0.0
vc-file-getprop 5 0.0 0.0
vc-bzr-registered 1 0.0 0.0
vc-svn-registered 1 0.0 0.0
vc-make-backend-sym 15 0.0 0.0
你能看出区别吗?:)
现在 Emacs 下的 Git 快得多了，但它仍然比 Emacs 下的 CVS 慢得多.所以我不知道为什么 Git 被称为快速版本控制系统".它可能比 CVS 更好，但更快?
Git under Emacs is way faster now, but it still much much slower than CVS under Emacs. So I have no idea why Git is called the "Fast Version Control System". It may be better than CVS, but faster?
推荐答案
有一个名为 ELP 的内置分析器.你可以试试M-x elp-instrument-package之类的，输入vc"，然后尝试找文件.之后，M-x elp-results 将向您显示一份个人资料报告.
There's a built-in profiler called ELP. You can try something like M-x elp-instrument-package, enter "vc", and then try finding a file. Afterwards, M-x elp-results will show you a profile report.
(请注意，如果时间花在与 vc 无关的功能上，则此技术不会显示它，但如果您愿意，可以检测更多包.)
(Note that if the time is instead being spent in non-vc-related functions, this technique will not show it, but you can instrument further packages if you like.)
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