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Posted to dev@zookeeper.apache.org by "Kezhu Wang (Jira)" <ji...@apache.org> on 2022/02/11 04:10:00 UTC
[jira] [Created] (ZOOKEEPER-4466) Watchers of different modes interfere on overlapping pathes
Kezhu Wang created ZOOKEEPER-4466:
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Summary: Watchers of different modes interfere on overlapping pathes
Key: ZOOKEEPER-4466
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-4466
Project: ZooKeeper
Issue Type: Bug
Components: java client, server
Affects Versions: 3.6.3, 3.7, 3.6.4
Reporter: Kezhu Wang
I used to think watchers of different modes are orthogonal. I found there are not, when I wrote tests for unfinished rust client. And I wrote [test cases|https://github.com/kezhuw/zookeeper/commit/79b05a95d2669a4acd16a4d544f24e2083a264f2#diff-8d31d27ea951fbc1f4fbda48d45748318f7124502839d825b77ad3fb8551bf43L152] in java and confirmed.
I copied test case here for evaluation. You also clone from [my fork|https://github.com/kezhuw/zookeeper/tree/watch-overlapping-path-with-different-modes-test-case].
{code:java}
// zookeeper-server/src/test/java/org/apache/zookeeper/test/PersistentRecursiveWatcherTest.java
@Test
public void testPathOverlapWithStandardWatcher() throws Exception {
try (ZooKeeper zk = createClient(new CountdownWatcher(), hostPort)) {
CountDownLatch nodeCreated = new CountDownLatch(1);
zk.addWatch("/a", persistentWatcher, PERSISTENT_RECURSIVE);
zk.exists("/a", event -> nodeCreated.countDown());
zk.create("/a", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
zk.create("/a/b", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
zk.delete("/a/b", -1);
zk.delete("/a", -1);
assertEvent(events, Watcher.Event.EventType.NodeCreated, "/a");
assertEvent(events, Watcher.Event.EventType.NodeCreated, "/a/b");
assertEvent(events, Watcher.Event.EventType.NodeDeleted, "/a/b");
assertEvent(events, Watcher.Event.EventType.NodeDeleted, "/a");
assertTrue(nodeCreated.await(5, TimeUnit.SECONDS));
}
}
@Test
public void testPathOverlapWithPersistentWatcher() throws Exception {
try (ZooKeeper zk = createClient(new CountdownWatcher(), hostPort)) {
zk.addWatch("/a", persistentWatcher, PERSISTENT_RECURSIVE);
zk.addWatch("/a/b", event -> {}, PERSISTENT);
zk.create("/a", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
zk.create("/a/b", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
zk.create("/a/b/c", new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
zk.delete("/a/b/c", -1);
zk.delete("/a/b", -1);
zk.delete("/a", -1);
assertEvent(events, Watcher.Event.EventType.NodeCreated, "/a");
assertEvent(events, Watcher.Event.EventType.NodeCreated, "/a/b");
assertEvent(events, Watcher.Event.EventType.NodeCreated, "/a/b/c");
assertEvent(events, Watcher.Event.EventType.NodeDeleted, "/a/b/c");
assertEvent(events, Watcher.Event.EventType.NodeDeleted, "/a/b");
assertEvent(events, Watcher.Event.EventType.NodeDeleted, "/a");
}
}
{code}
I skimmed the code and found two possible causes:
# {{ZKWatchManager.materialize}} materializes all persistent watchers(include recursive ones) for {{NodeChildrenChanged}} event.
# {{WatcherModeManager}} trackes only one watcher mode.
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