presto-main/src/main/java/io/prestosql/execution/SplitConcurrencyController.java/SplitConcurrencyController/SplitConcurrencyController
class SplitConcurrencyController:    public SplitConcurrencyController(int initialConcurrency, Duration adjustmentInterval)
    {
        checkArgument(initialConcurrency > 0, "initial concurrency must be positive");
        this.targetConcurrency = initialConcurrency;
        this.adjustmentIntervalNanos = adjustmentInterval.roundTo(NANOSECONDS);
    }