YongGoose commented on code in PR #7349:
URL: https://github.com/apache/incubator-seata/pull/7349#discussion_r2095714511
##########
discovery/seata-discovery-etcd3/src/main/java/org/apache/seata/discovery/registry/etcd3/EtcdRegistryServiceImpl.java:
##########
@@ -401,20 +411,24 @@ public EtcdWatcher(String cluster, Watch.Listener
listener) {
@Override
public void run() {
Watch watchClient = getClient().getWatchClient();
- WatchOption.Builder watchOptionBuilder =
WatchOption.newBuilder().withPrefix(buildRegistryKeyPrefix(cluster));
+ WatchOption.Builder watchOptionBuilder =
+
WatchOption.newBuilder().withPrefix(buildRegistryKeyPrefix(cluster));
Pair<Long /*revision*/, List<InetSocketAddress>> addressPair =
clusterAddressMap.get(cluster);
if (Objects.nonNull(addressPair)) {
// Maybe addressPair isn't newest now, but it's ok
watchOptionBuilder.withRevision(addressPair.getKey());
}
- this.watcher = watchClient.watch(buildRegistryKeyPrefix(cluster),
watchOptionBuilder.build(), this.listener);
+ this.watcher =
+ watchClient.watch(buildRegistryKeyPrefix(cluster),
watchOptionBuilder.build(), this.listener);
}
/**
* stop this task
*/
public void stop() {
- this.watcher.close();
+ if (this.watcher != null) {
+ this.watcher.close();
+ }
Review Comment:
Currently, the `watcher` is initialized not in the `constructor`, but within
the `run` method of the `EtcdWatcher` class.
In the test code, we used `thenAnswer` to return a `mockWatcher`, ensuring
that the watcher is properly initialized in the run method. However, when
running the test `10,000` times using `@RepeatedTest`, we encountered 7
failures.
All 7 failures were caused by a `NullPointerException` triggered when the
`stop` method was called while the watcher was still null.
It appears that, intermittently, the unsubscribe method is executed before
the run method, leading to this issue.
- After adding a null check in the `stop` method, the issue has not occurred
again.\
That's why i believe this piece of code is related to the NPE issue.
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