Support unlimited number of parallel jobs #1379

[martell]

Hey @nico,

I am looking to add a new mode, possibly a value passed to -j (or reading an environment variable to decide to enable this special mode or not) that runs as many parallel tasks as possible.
The easy way would be to just pass -j 1000 or something silly but I would like to actually get the number of concurrent tasks possible, which depends on the project, it could be limited by one part of a build depending on something previous being built and linked by the same project

Looking through the code, wanted_edges_ and command_edges_ pop out in src/build.cc
Could i get your input on how I would achieve this mode?

I assume this part is not possible because ninja just does what the it is told by the script but is there a way to differentiate between compile and link jobs for this.

Best,
Martell

[ilyapopov]

Can you use pools feature for this? Cmake allows you to configure pools for compilation and linking https://cmake.org/cmake/help/v3.9/prop_gbl/JOB_POOLS.html

[martell]

@ilyapopov this is not something I want to do at the cmake level.
I want ninja to just run every task it possibly can in parallel which should not be too difficult.

CC @bradking would probably know best what to do here :)

[bradking]

@martell take a look at RealCommandRunner::CanRunMore.

[mathstuf]

Make does this by using -j0 to do it.

[nico]

To me, passing -j 1000 is a good way to do this. It's understandable.

Supporting -j 0 would be consistent with -k 0 (which I'm not in love with; -k 100000 does the same and is more understandable – but we have -k 0 and won't take it away).

I think #1358 implements something like that.