presto-main/src/main/java/io/prestosql/operator/PipelineContext.java/PipelineContext/addDriverContext
class PipelineContext:    public DriverContext addDriverContext(Lifespan lifespan)
    {
        DriverContext driverContext = new DriverContext(
                this,
                notificationExecutor,
                yieldExecutor,
                pipelineMemoryContext.newMemoryTrackingContext(),
                lifespan);
        drivers.add(driverContext);
        return driverContext;
    }