Re: [PATCH] Enable parallelism in git submodule update.

[Phil Hord <phil.hord@gmail.com>]

On Sat, Nov 3, 2012 at 11:42 AM, Jens Lehmann <Jens.Lehmann@web.de> wrote:
> Am 30.10.2012 19:11, schrieb Stefan Zager:
>> This is a refresh of a conversation from a couple of months ago.
>>
>> I didn't try to implement all the desired features (e.g., smart logic
>> for passing a -j parameter to recursive submodule invocations), but I
>> did address the one issue that Junio insisted on: the code makes a
>> best effort to detect whether xargs supports parallel execution on the
>> host platform, and if it doesn't, then it prints a warning and falls
>> back to serial execution.
>
> I suspect not passing on --jobs recursively like you do here is the
> right thing to do, as that would give exponential growth of jobs with
> recursion depth, which makes no sense to me.

On the other hand, since $jobs is still defined when the recursive
call to is made to 'eval cmd_update "$orig_flags"', I suspect the
value *is* passed down recursively.  Maybe $jobs should be manually
reset before recursing -- unless it is "0" -- though I expect someone
would feel differently if she had one submodule on level 1 and 10
submodules on level 2.  She would be surprised, then, when  --jobs=10
seemed to have little affect on performance.  So maybe it is best to
leave it as it is, excepting that the apparent attempt not to pass the
switch down is probably misleading.

Phil