Github user kayousterhout commented on a diff in the pull request: https://github.com/apache/spark/pull/14079#discussion_r72502080 --- Diff: core/src/main/scala/org/apache/spark/scheduler/BlacklistTracker.scala --- @@ -0,0 +1,214 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 org.apache.spark.scheduler + +import java.util.concurrent.atomic.AtomicReference + +import scala.collection.mutable.{HashMap, HashSet} + +import org.apache.spark.SparkConf +import org.apache.spark.internal.Logging +import org.apache.spark.internal.config +import org.apache.spark.util.{Clock, SystemClock, Utils} + +/** + * BlacklistTracker is designed to track problematic executors and nodes. It supports blacklisting + * specific (executor, task) pairs within a stage, blacklisting entire executors and nodes for a + * stage, and blacklisting executors and nodes across an entire application (with a periodic + * expiry). + * + * The tracker needs to deal with a variety of workloads, eg.: bad user code, which may lead to many + * task failures, but that should not count against individual executors; many small stages, which + * may prevent a bad executor for having many failures within one stage, but still many failures + * over the entire application; "flaky" executors, that don't fail every task, but are still + * faulty; etc. + * + * THREADING: As with most helpers of TaskSchedulerImpl, this is not thread-safe. Though it is + * called by multiple threads, callers must already have a lock on the TaskSchedulerImpl. The + * one exception is [[nodeBlacklist()]], which can be called without holding a lock. + */ +private[scheduler] class BlacklistTracker ( + conf: SparkConf, + clock: Clock = new SystemClock()) extends Logging { + + private val MAX_FAILURES_PER_EXEC = conf.get(config.MAX_FAILURES_PER_EXEC) + private val MAX_FAILED_EXEC_PER_NODE = conf.get(config.MAX_FAILED_EXEC_PER_NODE) + val EXECUTOR_RECOVERY_MILLIS = BlacklistTracker.getBlacklistExpiryTime(conf) + + // a count of failed tasks for each executor. Only counts failures after tasksets complete + // successfully + private val executorIdToFailureCount: HashMap[String, Int] = new HashMap() + private val executorIdToBlacklistStatus: HashMap[String, BlacklistedExecutor] = new HashMap() + private val nodeIdToBlacklistExpiryTime: HashMap[String, Long] = new HashMap() + private val _nodeBlacklist: AtomicReference[Set[String]] = new AtomicReference(Set()) + private var nextExpiryTime: Long = Long.MaxValue + // for blacklisted executors, the node it is on. We do *not* remove from this when executors are + // removed from spark, so we can track when we get multiple successive blacklisted executors on + // one node. + val nodeToFailedExecs: HashMap[String, HashSet[String]] = new HashMap() + + def expireExecutorsInBlacklist(): Unit = { + val now = clock.getTimeMillis() + // quickly check if we've got anything to expire from blacklist -- if not, avoid doing any work + if (now > nextExpiryTime) { + val execsToClear = executorIdToBlacklistStatus.filter(_._2.expiryTime < now).keys + if (execsToClear.nonEmpty) { + logInfo(s"Removing executors $execsToClear from blacklist during periodic recovery") --- End diff -- Removing nodes $nodesToClear from blacklist because the blacklist has expired (or "timed out")?
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