[Webkit-unassigned] [Bug 37377] Don't reinvent Executive.cpu_count for every port

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=37377





--- Comment #7 from Adam Barth <abarth at webkit.org>  2010-04-10 07:56:46 PST ---
> > +        if platform.system() == "Dawin" and options.num_dump_render_trees > 4:
> > +            options.num_dump_render_trees = 4
> 
> The instability isn't generic, it's port-specific, and there should be a
> port-specific way to limit parallelism. For example, the fact that the base mac 
> port is unstable due to DumpRenderTree doesn't mean that we should limit the
> parallelism that Chromoium gets.

Ok.  It seems better to just fix the bug than to create something complicated
to work around the issue.

> I think a better way to implement this patch would've been to have
> base.num_cores() call the Executive module, and leave the hook in for any ports
> that didn't want the default logic.

How about a base.default_dump_render_tree_count method?  The number of cores
your machine has doesn't vary by port, but the number of DRT instances you want
could.

> I went pretty far ensuring that anything platform-specific needed by
> run-webkit-tests would be wrapped up in the Port interface, so that a Port only
> needs to change things in one place. The rest of the Python code does not seem
> to have a similar since of layering (as evidenced by the switch statement in
> system/executive.py). Please don't undo this layering without replacing it with
> something equivalent or at least having more of a discussion about this.

There's really two things going on.  We have a notion of a port (Gtk, Chromium,
Qt, etc) and a notion of  a platform (Mac, Windows, Linux).  At the moment, the
two are smashed together, which leads to the copy/paste code.

In this particular case, the OS-specific code is just making up for a
deficiency in the Python 2.5 library.  In Python 2.6, the multiprocessing
package abstracts away the platform specific logic for counting CPUs.

In any case, I'll write a patch that I think will make you happy.  :)

> > @@ -1461,9 +1470,9 @@ def main(options, args):
> >          # Creating the expecations for each platform/configuration pair does
> >          # all the test list parsing and ensures it's correct syntax (e.g. no
> >          # dupes).
> > -        for platform in port_obj.test_platform_names():
> > -            test_runner.parse_expectations(platform, is_debug_mode=True)
> > -            test_runner.parse_expectations(platform, is_debug_mode=False)
> > +        for platform_name in port_obj.test_platform_names():
> > +            test_runner.parse_expectations(platform_name, is_debug_mode=True)
> > +            test_runner.parse_expectations(platform_name, is_debug_mode=False)
> >          meter.update("")
> >          print ("If there are no fail messages, errors or exceptions, then the "
>
> I have no objection to this change, but it doesn't seem to have anything to do
> with the rest of this patch. Did it sneak in accidentally?

The name "platform" conflicts with the import platform statements I added at
the top of the file.

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