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IDProjectCategoryView StatusDate SubmittedLast Update
0005201OCamlOCamlbuild (the tool)public2011-01-04 16:292012-12-15 18:11
Reporterdaweil 
Assigned Toxclerc 
PrioritynormalSeveritytweakReproducibilityalways
StatusassignedResolutionopen 
PlatformWindowsOSXPOS Version2
Product Version3.12.0 
Target Version4.01.0+devFixed in Version 
Summary0005201: Performance issue for ocamlbuild on Windows
Descriptionon Windows system, each command executed by ocambuild is encapsulated in a "bash -C" command which has a non negligeable overhead (~ 0.5s).
Unless the Filename.quote function is fixed, a simple improvement is to change a line in file ocamlbuild/my_std.ml,
In function sys_command, just replace the line
 let cmd = "bash -c "^Filename.quote cmd in

by
  let cmd = "sh -c "^Filename.quote cmd in

ocamlbuild will go much faster on Windows.

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-  Notes
(0005759)
ertai (developer)
2011-01-05 16:19

In the same vein I would also be in favor of not calling the shell when the arguments are either easily quotable or need not to be quoted.
(0008124)
daweil (reporter)
2012-09-20 14:11

and because ocamlbuild call the "bash" or the "sh" shell, ocamlbuild does'nt work when call direcly called from a DOS shell.
So this issue is not only a performance issue.
(0008125)
protz (manager)
2012-09-20 14:17

Yes, however, the recommend way to run OCaml under Windows is inside a Cygwin environment (either with the cygwin-packaged ocaml, or the native win32 ocaml compilers) so that you have a shell and the gnu tools available to work with. Argument quoting is such a mess on windows that I don't think it would be easy to make sure ocamlbuild can rely on cmd.exe under windows...
(0008126)
ygrek (reporter)
2012-09-20 15:04

FTR see the discussion and referenced articles at https://forge.ocamlcore.org/tracker/?func=detail&aid=1170&group_id=54&atid=291 [^]
(0008615)
Camarade_Tux (reporter)
2012-12-15 18:05
edited on: 2012-12-15 18:12

I've started to look at the issue a bit more in-depth.

ocamlbuild uses this for different kinds of commands:
1- calls to cp, rm, mkdir, find, ...
2- any command through "run_and_read" or "run_and_open" functions which start a process and retrieve its standard output

1- is probably the biggest performance killer by far, especially on windows. Spawning bash on msys or cygwin takes time and spawning another command will only be slower. These should be pretty easy to implement.

2- is more annoying. The functions "run_and_*" seem to be usable by plugins but maybe not officially (can someone confirm this?). Overall it would be nicer to avoid such functions or reduce their number (some are easy: there's a call to readlink).

There will still be a few calls ("ocamlfind list" for instance) anyway. In ygrek's link, thelema has implemented the necessary quoting in ocaml; would it be possible to include this in the standard library? Unix.exec* functions should also be rewritten to use that quoting.

Moving the run_and_* functions from ocamlbuild to the standard library would probably be good too since they're already in the ocaml sources and are needed by projects which cannot easily use an additional library (ocamlbuild, my yypkg package manager, probably omake, ocamlfind, godi, ...).

So, does removing as many calls to external commands as possible and adding support for proper quoting for processes in the standard library sound like a good way?

PS: this issue should be made linked to "0004981: ocamlbuild/my_std.ml shouldn't call bash" in mantis.


- Issue History
Date Modified Username Field Change
2011-01-04 16:29 daweil New Issue
2011-01-05 16:19 ertai Note Added: 0005759
2011-01-05 16:19 ertai Assigned To => xclerc
2011-01-05 16:19 ertai Status new => assigned
2012-02-02 15:17 protz Category OCamlbuild => OCamlbuild (the tool)
2012-07-10 17:17 doligez Target Version => 4.01.0+dev
2012-07-31 13:36 doligez Target Version 4.01.0+dev => 4.00.1+dev
2012-09-19 14:57 doligez Severity minor => tweak
2012-09-19 14:57 doligez Target Version 4.00.1+dev => 4.01.0+dev
2012-09-20 14:11 daweil Note Added: 0008124
2012-09-20 14:17 protz Note Added: 0008125
2012-09-20 15:04 ygrek Note Added: 0008126
2012-12-15 18:05 Camarade_Tux Note Added: 0008615
2012-12-15 18:12 Camarade_Tux Note Edited: 0008615 View Revisions


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