Regression metric keys

The metric keys that a regression metric or regression budget accepts.

--regression-metric, --regression-budget and the --budgets file (and the MCP evaluate_budgets tool's regressionMetric) take one of these keys; the default for --regression-metric is wallClock:

• wallClock: wall-clock duration
• executorRunTime: summed executor run time
• shuffleSpill: memory spill (Spark's memoryBytesSpilled)
• diskSpill: disk spill (Spark's diskBytesSpilled)
• gcTime: JVM GC time
• taskSkew: p95 task skew
• failedTaskRate: failed-task rate
• executorCpuTime: summed executor CPU time, in milliseconds (unavailable for a run whose log never recorded it)
• allocatedCoreHours: executor cores times hours alive, see Allocation

Four more keys, inputBytes, outputBytes, taskCount and executorsAdded, measure workload volume rather than performance. They have no better or worse direction, so a regression budget on one of them reports inconclusive whenever the value changes, and passes when it doesn't.