io.trino.execution.scheduler.faulttolerant.TaskExecutionClass Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.trino.execution.scheduler.faulttolerant;
public enum TaskExecutionClass
{
// Tasks from stages with all upstream stages finished
STANDARD,
// Tasks from stages with some upstream stages still running.
// To be scheduled only if no STANDARD tasks can fit.
// Picked to kill if worker runs out of memory to prevent deadlock.
SPECULATIVE,
// Tasks from stages with some upstream stages still running but with high priority.
// Will be scheduled even if there are resources to schedule STANDARD tasks on cluster.
// Tasks of EAGER_SPECULATIVE are used to implement early termination of queries, when it
// is probable that we do not need to run whole downstream stages to produce final query result.
// EAGER_SPECULATIVE will not prevent STANDARD tasks from being scheduled and will still be picked
// to kill if needed when worker runs out of memory; this is needed to prevent deadlocks.
EAGER_SPECULATIVE,
/**/;
boolean canTransitionTo(TaskExecutionClass targetExecutionClass)
{
return switch (this) {
case STANDARD -> targetExecutionClass == STANDARD;
case SPECULATIVE -> targetExecutionClass == SPECULATIVE || targetExecutionClass == STANDARD;
case EAGER_SPECULATIVE -> targetExecutionClass == EAGER_SPECULATIVE || targetExecutionClass == STANDARD;
};
}
boolean isSpeculative()
{
return switch (this) {
case STANDARD -> false;
case SPECULATIVE, EAGER_SPECULATIVE -> true;
};
}
}