m-trieu commented on code in PR #28835: URL: https://github.com/apache/beam/pull/28835#discussion_r1402805667
########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/work/budget/GetWorkBudgetRefresher.java: ########## @@ -0,0 +1,132 @@ +/* + * 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.beam.runners.dataflow.worker.windmill.work.budget; + +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.TimeoutException; +import java.util.function.Supplier; +import javax.annotation.concurrent.ThreadSafe; +import org.apache.beam.sdk.annotations.Internal; +import org.apache.beam.sdk.fn.stream.AdvancingPhaser; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.ThreadFactoryBuilder; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Handles refreshing the budget either via triggered or scheduled execution using a {@link + * java.util.concurrent.Phaser} to emulate publish/subscribe pattern. + */ +@Internal +@ThreadSafe +public final class GetWorkBudgetRefresher { + @VisibleForTesting public static final int SCHEDULED_BUDGET_REFRESH_MILLIS = 100; + private static final int INITIAL_BUDGET_REFRESH_PHASE = 0; + private static final String BUDGET_REFRESH_THREAD = "GetWorkBudgetRefreshThread"; + private static final Logger LOG = LoggerFactory.getLogger(GetWorkBudgetRefresher.class); + + private final AdvancingPhaser budgetRefreshTrigger; + private final ExecutorService budgetRefreshExecutor; + private final Supplier<Boolean> isBudgetRefreshPaused; + private final Runnable redistributeBudget; + + public GetWorkBudgetRefresher( + Supplier<Boolean> isBudgetRefreshPaused, Runnable redistributeBudget) { + this.budgetRefreshTrigger = new AdvancingPhaser(1); + this.budgetRefreshExecutor = + Executors.newSingleThreadScheduledExecutor( + new ThreadFactoryBuilder() + .setNameFormat(BUDGET_REFRESH_THREAD) + .setUncaughtExceptionHandler( + (t, e) -> + LOG.error( + "{} failed due to uncaught exception during execution. ", + t.getName(), + e)) + .build()); + this.isBudgetRefreshPaused = isBudgetRefreshPaused; + this.redistributeBudget = redistributeBudget; + } + + @SuppressWarnings("FutureReturnValueIgnored") + public void start() { + budgetRefreshExecutor.submit(this::subscribeToRefreshBudget); + } + + /** Publishes an event to trigger a budget refresh. */ + public synchronized void requestBudgetRefresh() { + budgetRefreshTrigger.arrive(); + } + + public void stop() { + budgetRefreshTrigger.arriveAndDeregister(); + // Put the budgetRefreshTrigger in a terminated state, #waitForBudgetRefreshEventWithTimeout + // will subsequently return false, and #subscribeToRefreshBudget will return, completing the + // task. + budgetRefreshTrigger.forceTermination(); + budgetRefreshExecutor.shutdownNow(); + } + + private void subscribeToRefreshBudget() { + int currentBudgetRefreshPhase = INITIAL_BUDGET_REFRESH_PHASE; + // Runs forever until #stop is called. + while (true) { + currentBudgetRefreshPhase = waitForBudgetRefreshEventWithTimeout(currentBudgetRefreshPhase); + // Phaser.awaitAdvanceInterruptibly(...) returns a negative value if the phaser is + // terminated, else returns when either a budget refresh has been manually triggered or + // SCHEDULED_BUDGET_REFRESH_MILLIS have passed. + if (currentBudgetRefreshPhase < 0) { + return; + } + // Budget refreshes are paused during endpoint updates. + if (!isBudgetRefreshPaused.get()) { + redistributeBudget.run(); + } + } + } + + /** + * Waits for a budget refresh trigger event with a timeout. Returns whether budgets should still + * be refreshed. + * + * <p>Budget refresh event is triggered when {@link #budgetRefreshTrigger} moves on from the given + * currentBudgetRefreshPhase. + */ + private int waitForBudgetRefreshEventWithTimeout(int currentBudgetRefreshPhase) { + try { + // Wait for budgetRefreshTrigger to advance FROM the current phase. + return budgetRefreshTrigger.awaitAdvanceInterruptibly( + currentBudgetRefreshPhase, SCHEDULED_BUDGET_REFRESH_MILLIS, TimeUnit.MILLISECONDS); + } catch (TimeoutException e) { + LOG.info("Budget refresh not triggered, proceeding with scheduled refresh."); Review Comment: removed -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
