#19916

Committed 18 Jul 2025 04:05PM UTC coverage: 88.586% (+0.006%) from 88.58%

Build # #19916

Build Type

push

github

Committed by

ejona86

Commit Message

LBs should avoid calling LBs after lb.shutdown()

LoadBalancers shouldn't be called after shutdown(), but RingHashLb could
have enqueued work to the SynchronizationContext that executed after
shutdown(). This commit fixes problems discovered when auditing all LBs
usage of the syncContext for that type of problem.

Similarly, PickFirstLb could have requested a new connection after
shutdown(). We want to avoid that sort of thing too.

RingHashLb's test changed from CONNECTING to TRANSIENT_FAILURE to get
the latest picker. Because two subchannels have failed it will be in
TRANSIENT_FAILURE. Previously the test was using an older picker with
out-of-date subchannelView, and the verifyConnection() was too imprecise
to notice it was creating the wrong subchannel.

As discovered in b/430347751, where ClusterImplLb was seeing a new
subchannel being called after the child LB was shutdown (the shutdown
itself had been caused by RingHashConfig not implementing equals() and
was fixed by a8de9f07ab, which caused ClusterResolverLb to replace its
state):

```
java.lang.NullPointerException
	at io.grpc.xds.ClusterImplLoadBalancer$ClusterImplLbHelper.createClusterLocalityFromAttributes(ClusterImplLoadBalancer.java:322)
	at io.grpc.xds.ClusterImplLoadBalancer$ClusterImplLbHelper.createSubchannel(ClusterImplLoadBalancer.java:236)
	at io.grpc.util.ForwardingLoadBalancerHelper.createSubchannel(ForwardingLoadBalancerHelper.java:47)
	at io.grpc.util.ForwardingLoadBalancerHelper.createSubchannel(ForwardingLoadBalancerHelper.java:47)
	at io.grpc.internal.PickFirstLeafLoadBalancer.createNewSubchannel(PickFirstLeafLoadBalancer.java:527)
	at io.grpc.internal.PickFirstLeafLoadBalancer.requestConnection(PickFirstLeafLoadBalancer.java:459)
	at io.grpc.internal.PickFirstLeafLoadBalancer.acceptResolvedAddresses(PickFirstLeafLoadBalancer.java:174)
	at io.grpc.xds.LazyLoadBalancer$LazyDelegate.activate(LazyLoadBalancer.java:64)
	at io.grpc.xds.LazyLoadBalancer$LazyDelegate.requestConnec... (continued)

Run Details

34653 of 39118 relevant lines covered (88.59%)

0.89 hits per line

Source File
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87.88

/../netty/src/main/java/io/grpc/netty/ClientTransportLifecycleManager.java

/*
 * Copyright 2016 The gRPC Authors
 *
 * Licensed 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 io.grpc.netty;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import io.grpc.Attributes;
import io.grpc.Status;
import io.grpc.internal.ManagedClientTransport;

/** Maintainer of transport lifecycle status. */
final class ClientTransportLifecycleManager {
  private final ManagedClientTransport.Listener listener;
  private boolean transportReady;
  private boolean transportShutdown;
  private boolean transportInUse;
  /** null iff !transportShutdown. */
  private Status shutdownStatus;
  /** null iff !transportShutdown. */
  private boolean transportTerminated;

  public ClientTransportLifecycleManager(ManagedClientTransport.Listener listener) {
    this.listener = listener;
  }

  public Attributes filterAttributes(Attributes attributes) {
    if (transportReady || transportShutdown) {
      return attributes;
    }
    return listener.filterTransport(attributes);
  }

  public void notifyReady() {
    if (transportReady || transportShutdown) {
      return;
    }
    transportReady = true;
    listener.transportReady();
  }

  /**
   * Marks transport as shutdown, but does not set the error status. This must eventually be
   * followed by a call to notifyShutdown.
   */
  public void notifyGracefulShutdown(Status s) {
    if (transportShutdown) {
      return;
    }
    transportShutdown = true;
    listener.transportShutdown(s);
  }

  /** Returns {@code true} if was the first shutdown. */
  @CanIgnoreReturnValue
  public boolean notifyShutdown(Status s) {
    notifyGracefulShutdown(s);
    if (shutdownStatus != null) {
      return false;
    }
    shutdownStatus = s;
    return true;
  }

  public void notifyInUse(boolean inUse) {
    if (inUse == transportInUse) {
      return;
    }
    transportInUse = inUse;
    listener.transportInUse(inUse);
  }

  public void notifyTerminated(Status s) {
    if (transportTerminated) {
      return;
    }
    transportTerminated = true;
    notifyShutdown(s);
    listener.transportTerminated();
  }

  public Status getShutdownStatus() {
    return shutdownStatus;
  }

}

1	/*
2	* Copyright 2016 The gRPC Authors
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16
17	package io.grpc.netty;
18
19	import com.google.errorprone.annotations.CanIgnoreReturnValue;
20	import io.grpc.Attributes;
21	import io.grpc.Status;
22	import io.grpc.internal.ManagedClientTransport;
23
24	/** Maintainer of transport lifecycle status. */
25	final class ClientTransportLifecycleManager {
26	private final ManagedClientTransport.Listener listener;
27	private boolean transportReady;
28	private boolean transportShutdown;
29	private boolean transportInUse;
30	/** null iff !transportShutdown. */
31	private Status shutdownStatus;
32	/** null iff !transportShutdown. */
33	private boolean transportTerminated;
34
35	public ClientTransportLifecycleManager(ManagedClientTransport.Listener listener) {	1✔
36	this.listener = listener;	1✔
37	}	1✔
38
39	public Attributes filterAttributes(Attributes attributes) {
40	if (transportReady \|\| transportShutdown) {	1✔
41	return attributes;	×
42	}
43	return listener.filterTransport(attributes);	1✔
44	}
45
46	public void notifyReady() {
47	if (transportReady \|\| transportShutdown) {	1✔
48	return;	×
49	}
50	transportReady = true;	1✔
51	listener.transportReady();	1✔
52	}	1✔
53
54	/**
55	* Marks transport as shutdown, but does not set the error status. This must eventually be
56	* followed by a call to notifyShutdown.
57	*/
58	public void notifyGracefulShutdown(Status s) {
59	if (transportShutdown) {	1✔
60	return;	1✔
61	}
62	transportShutdown = true;	1✔
63	listener.transportShutdown(s);	1✔
64	}	1✔
65
66	/** Returns {@code true} if was the first shutdown. */
67	@CanIgnoreReturnValue
68	public boolean notifyShutdown(Status s) {
69	notifyGracefulShutdown(s);	1✔
70	if (shutdownStatus != null) {	1✔
71	return false;	1✔
72	}
73	shutdownStatus = s;	1✔
74	return true;	1✔
75	}
76
77	public void notifyInUse(boolean inUse) {
78	if (inUse == transportInUse) {	1✔
79	return;	×
80	}
81	transportInUse = inUse;	1✔
82	listener.transportInUse(inUse);	1✔
83	}	1✔
84
85	public void notifyTerminated(Status s) {
86	if (transportTerminated) {	1✔
87	return;	×
88	}
89	transportTerminated = true;	1✔
90	notifyShutdown(s);	1✔
91	listener.transportTerminated();	1✔
92	}	1✔
93
94	public Status getShutdownStatus() {
95	return shutdownStatus;	1✔
96	}
97
98	}

grpc / grpc-java / #19916

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