From e619e9ac36474fb93b4e85436e2f14ed2927be0f Mon Sep 17 00:00:00 2001 From: Qiang Zhao Date: Thu, 9 Mar 2023 10:17:39 +0800 Subject: [PATCH 1/2] [fix][meta] Fix deadlock causes session notification not to work (#19754) ### Motivation This is a namespace bundle double-owners problem. We found it in the memory dumps. The memory dumps show that the notification thread has been blocked for a long time by the leader election deadlock, And many notifications are blocked in the executor queue. This causes we can't to revalidate the locks, and they are still thinking them working well. For private reasons, I can't share the namespace bundle snapshot, but the blocked thread easily explains it. image ^^ blocked thread image ^^ executor queue ### Modifications - Avoid putting the new task to single thread executor causes deadlock. (cherry picked from commit cbd799f05eb26aeac5ffd5bbb9751ad9e5928dd3) --- .../coordination/impl/LeaderElectionImpl.java | 10 ++- .../impl/LeaderElectionImplTest.java | 65 +++++++++++++++++++ 2 files changed, 73 insertions(+), 2 deletions(-) create mode 100644 pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java diff --git a/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImpl.java b/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImpl.java index 86fac33f7c2c9..8e1d2cd4aa756 100644 --- a/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImpl.java +++ b/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImpl.java @@ -19,6 +19,7 @@ package org.apache.pulsar.metadata.coordination.impl; import com.fasterxml.jackson.databind.type.TypeFactory; +import com.google.common.annotations.VisibleForTesting; import java.util.EnumSet; import java.util.Optional; import java.util.concurrent.CompletableFuture; @@ -111,13 +112,13 @@ private synchronized CompletableFuture elect() { } else { return tryToBecomeLeader(); } - }).thenComposeAsync(leaderElectionState -> { + }).thenCompose(leaderElectionState -> { // make sure that the cache contains the current leader // so that getLeaderValueIfPresent works on all brokers cache.refresh(path); return cache.get(path) .thenApply(__ -> leaderElectionState); - }, executor); + }); } private synchronized CompletableFuture handleExistingLeaderValue(GetResult res) { @@ -336,4 +337,9 @@ private void handlePathNotification(Notification notification) { } } } + + @VisibleForTesting + protected ScheduledExecutorService getSchedulerExecutor() { + return executor; + } } diff --git a/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java b/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java new file mode 100644 index 0000000000000..027521d2ffc17 --- /dev/null +++ b/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java @@ -0,0 +1,65 @@ +/* + * 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.pulsar.metadata.coordination.impl; + +import java.util.concurrent.CompletableFuture; +import java.util.function.Supplier; +import lombok.Cleanup; +import org.apache.pulsar.metadata.BaseMetadataStoreTest; +import org.apache.pulsar.metadata.api.MetadataStoreConfig; +import org.apache.pulsar.metadata.api.coordination.CoordinationService; +import org.apache.pulsar.metadata.api.extended.MetadataStoreExtended; +import org.testng.annotations.Test; + +public class LeaderElectionImplTest extends BaseMetadataStoreTest { + + @Test(dataProvider = "impl", timeOut = 10000) + public void validateDeadLock(String provider, Supplier urlSupplier) + throws Exception { + if (provider.equals("Memory") || provider.equals("RocksDB")) { + // There are no multiple sessions for the local memory provider + return; + } + + @Cleanup + MetadataStoreExtended store = MetadataStoreExtended.create(urlSupplier.get(), + MetadataStoreConfig.builder().build()); + + String path = newKey(); + + @Cleanup + CoordinationService cs = new CoordinationServiceImpl(store); + + @Cleanup + LeaderElectionImpl le = (LeaderElectionImpl) cs.getLeaderElection(String.class, + path, __ -> { + }); + final CompletableFuture blockFuture = new CompletableFuture<>(); + // simulate handleSessionNotification method logic + le.getSchedulerExecutor().execute(() -> { + try { + le.elect("test-2").join(); + blockFuture.complete(null); + } catch (Throwable ex) { + blockFuture.completeExceptionally(ex); + } + }); + blockFuture.join(); + } +} From 5085e16fb3cd009a9ee4b5dc3d4f1f68c2cad903 Mon Sep 17 00:00:00 2001 From: xiangying <1984997880@qq.com> Date: Thu, 9 Mar 2023 22:28:41 +0800 Subject: [PATCH 2/2] license header --- .../metadata/coordination/impl/LeaderElectionImplTest.java | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java b/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java index 027521d2ffc17..8f70ab5195852 100644 --- a/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java +++ b/pulsar-metadata/src/test/java/org/apache/pulsar/metadata/coordination/impl/LeaderElectionImplTest.java @@ -1,4 +1,4 @@ -/* +/** * 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