Right now we're maxing out the number of workers. This tends to cause various issues such as test results being off by 1, flakiness, and occasional timeouts. Maxing out the number of threads might actually in some cases slow down the test cases rather than speed them up. Decreasing the number of workers to half the available cores (just to be on the safe side).
Created attachment 209918 [details] Patch
Comment on attachment 209918 [details] Patch Yes! r=me.
Awesome thanks, hopefully we'll start seeing some more stability in the bots now. Committed: https://trac.webkit.org/r154776