Re: [PATCH v3] meson: Pass -j option to sphinx

[Fabiano Rosas <farosas@suse.de>]

Markus Armbruster <armbru@redhat.com> writes:

> Fabiano Rosas <farosas@suse.de> writes:
>
>> Save a bit of build time by passing the number of jobs option to
>> sphinx.
>>
>> We cannot use the -j option from make because meson does not support
>> setting build time parameters for custom targets. Use nproc instead or
>> the equivalent sphinx option "-j auto", if that is available.
>>
>> Also make sure our plugins support parallelism and report it properly
>> to sphinx. Particularly, implement the merge_domaindata method in
>> DBusDomain that is used to merge in data from other subprocesses.
>>
>> before:
>>   $ time make man html
>>   ...
>>   [1/2] Generating docs/QEMU manual with a custom command
>>   [2/2] Generating docs/QEMU man pages with a custom command
>>
>>   real    0m43.157s
>>   user    0m42.642s
>>   sys     0m0.576s
>>
>> after:
>>   $ time make man html
>>   ...
>>   [1/2] Generating docs/QEMU manual with a custom command
>>   [2/2] Generating docs/QEMU man pages with a custom command
>>
>>   real    0m25.014s
>>   user    0m51.288s
>>   sys     0m2.085s
>
> Thanks for tackling this!  sphinx-build is so slow I disable doc
> building unless I'm working on docs.
>
>> Tested-by: Daniel P. Berrangé <berrange@redhat.com>
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>>  docs/meson.build           | 12 ++++++++++++
>>  docs/sphinx/dbusdomain.py  |  4 ++++
>>  docs/sphinx/fakedbusdoc.py |  5 +++++
>>  docs/sphinx/qmp_lexer.py   |  5 +++++
>>  4 files changed, 26 insertions(+)
>>
>> diff --git a/docs/meson.build b/docs/meson.build
>> index f220800e3e..138ec6ce6f 100644
>> --- a/docs/meson.build
>> +++ b/docs/meson.build
>> @@ -10,6 +10,18 @@ if sphinx_build.found()
>>      SPHINX_ARGS += [ '-W', '-Dkerneldoc_werror=1' ]
>>    endif
>>  
>> +  sphinx_version = run_command(SPHINX_ARGS + ['--version'],
>> +                               check: true).stdout().split()[1]
>> +  if sphinx_version.version_compare('>=5.1.2')
>
> Where do you get 5.1.2 from?  I have 5.0.2, and -j auto appears to work
> fine.  The manual page says "Changed in version 1.7: Support auto
> argument."
>

Ouch, I was looking at the readthedocs repository which has a similar
change.

So I think we could probably just hardcode the option. Most distros will
have a more recent sphinx version.
https://repology.org/project/python:sphinx/versions

Let me try to figure out what gitlab is using. I know it is less than 4
because our docs don't show some of the dbus parts:

https://www.qemu.org/docs/master/interop/dbus-display.html

>> +    SPHINX_ARGS += ['-j', 'auto']
>> +  else
>> +    nproc = find_program('nproc')
>> +    if nproc.found()
>> +      jobs = run_command(nproc, check: true).stdout()
>> +      SPHINX_ARGS += ['-j', jobs]
>> +    endif
>> +  endif
>> +
>>    # This is a bit awkward but works: create a trivial document and
>>    # try to run it with our configuration file (which enforces a
>>    # version requirement). This will fail if sphinx-build is too old.
>
> [...]