[ccache] parallel builds with a high cache hit kill the local host

[Timothee Besset]

Lo all.

I've been using "ccache distcc" for everyday work for quite some time now, and it's working great most of the time. However, I'm finding that ccache can be trouble with parallel building in some circumstances:

I run between 10 and 15 jobs for a build. I have enough CPUs around to distribute that fine with distcc. However, if I wipe out my build tree and rebuild, then ccache is going to catch most of the files in the build .. and start 15 processes on the local host, making it completely unresponsive for a while.

Is it possible to add a global lock count for ccache so the new processes wait for a free work slot before doing their thing? I'm not sure if that should be a startup lock, or a lock to check after the cache hit/miss decision. A global lock is probably best..

That's typically the kind of thing where a tighter integration of ccache and distcc would be good btw..

TTimo