caqhy opened a new issue, #21183:
URL: https://github.com/apache/shardingsphere/issues/21183
## Bug Report
### Use Etcd in cluster mode
1.The node that starts first can not see the logical database created by the
node that starts later
2.Throw NPE when processing events
```[ERROR] 2022-08-30 12:37:15.186 [grpc-default-executor-0]
c.g.common.eventbus.EventBus.default - Exception thrown by subscriber method
renew(org.apache.shardingsphere.mode.manager.cluster.coordinator.registry.config.event.datasource.DataSourceChangedEvent)
on subscriber
org.apache.shardingsphere.mode.manager.cluster.coordinator.ClusterContextManagerCoordinator@5438c17a
when dispatching event:
org.apache.shardingsphere.mode.manager.cluster.coordinator.registry.config.event.datasource.DataSourceChangedEvent@63f88bd4
java.lang.NullPointerException: null
at
org.apache.shardingsphere.mode.manager.ContextManager.getStaleResourceHeldRules(ContextManager.java:324)
at
org.apache.shardingsphere.mode.manager.ContextManager.alterDataSourceConfiguration(ContextManager.java:288)
at
org.apache.shardingsphere.mode.manager.cluster.coordinator.ClusterContextManagerCoordinator.renew(ClusterContextManagerCoordinator.java:162)
at
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at
com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:87)
at
com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:144)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:72)
at
com.google.common.util.concurrent.DirectExecutor.execute(DirectExecutor.java:30)
at
com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:67)
at
com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:108)
at com.google.common.eventbus.EventBus.post(EventBus.java:212)
at
org.apache.shardingsphere.infra.util.eventbus.EventBusContext.post(EventBusContext.java:51)
at java.base/java.util.Optional.ifPresent(Optional.java:183)
at
org.apache.shardingsphere.mode.manager.cluster.coordinator.registry.GovernanceWatcherFactory.lambda$watch$0(GovernanceWatcherFactory.java:59)
at
org.apache.shardingsphere.mode.repository.cluster.etcd.EtcdRepository.lambda$watch$2(EtcdRepository.java:140)
at io.etcd.jetcd.Watch$1.onNext(Watch.java:105)
at io.etcd.jetcd.WatchImpl$WatcherImpl.onNext(WatchImpl.java:248)
at io.etcd.jetcd.WatchImpl$WatcherImpl.onNext(WatchImpl.java:99)
at
io.grpc.stub.ClientCalls$StreamObserverToCallListenerAdapter.onMessage(ClientCalls.java:436)
at
io.grpc.ForwardingClientCallListener.onMessage(ForwardingClientCallListener.java:33)
at
io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1MessagesAvailable.runInternal(ClientCallImpl.java:658)
at
io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1MessagesAvailable.runInContext(ClientCallImpl.java:643)
at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
at
io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:123)
at
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
### Which version of ShardingSphere did you use?
latest master
### Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy?
ShardingSphere-Proxy
### Expected behavior
The node that starts first can see the logical database created by the node
that starts later.
### Actual behavior
The node that starts first can not see the logical database created by the
node that starts later.
### Reason analyze (If you can)
Etcd:
Because the parent path: `/metadata/databaseName` event is missing,
subsequent event processing throws NPE.
Where errors occur:
Zookeeper:
When persistent data is like
'/metadata/databaseName/versions/0/dataSources', Zookeeper server will
preferentially build parent path:`/metadata/databaseName` and broadcast this
event:`/metadata/databaseName` to client. During event:`/metadata/databaseName`
processing, the following code logic will be executed:
Therefore, subsequent events are handled normally.
### Solution
Etcd Client preferentially persists parent path.
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