7eb29367

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Add --mutation-coverage-jobs to cap coverage parallelism

Test suites with expensive per-test setup (e.g. tmp-postgres) can overwhelm
the system when getNumCapabilities children try to start at once. Expose
a knob to limit it.

mutationCheck.nix gets a coverageJobs argument that, when set, passes the
flag to both the first-suite and extra-suite coverage invocations.

Suite timing

Time to Start Worker time Duration Time to finish Idle
Config 0s 2s 2s 2s 0s
Eval 3s 38s 38s 41s 0s
Build 6s 25m47s - - 0s
Suite 0s 26m28s - - 121h28m31s

Timeline

0s1m2m3m4m5m6m