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KAFKA-17506 KRaftMigrationDriver initialization race (#17147) 

There is a race condition between KRaftMigrationDriver running its first poll() and being notified by Raft about a leader change. If onControllerChange is called before RecoverMigrationStateFromZKEvent is run, we will end up getting stuck in the INACTIVE state.

This patch fixes the race by enqueuing a RecoverMigrationStateFromZKEvent from onControllerChange if the driver has not yet initialized. If another RecoverMigrationStateFromZKEvent was already enqueued, the second one to run will just be ignored.

Reviewers: Luke Chen <showuon@gmail.com>
This commit is contained in:
David Arthur 2024-09-11 10:41:49 -04:00 committed by GitHub
parent d04f534892
commit 0e30209f01
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2 changed files with 31 additions and 2 deletions
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7
metadata/src/main/java/org/apache/kafka/metadata/migration/KRaftMigrationDriver.java
View File

@ -359,6 +359,9 @@ public class KRaftMigrationDriver implements MetadataPublisher {
@Override
public void onControllerChange(LeaderAndEpoch newLeaderAndEpoch) {
curLeaderAndEpoch = newLeaderAndEpoch;
if (migrationState.equals(MigrationDriverState.UNINITIALIZED)) {
eventQueue.append(new RecoverMigrationStateFromZKEvent());
}
eventQueue.append(new KRaftLeaderEvent(newLeaderAndEpoch));
}
@ -519,8 +522,8 @@ public class KRaftMigrationDriver implements MetadataPublisher {
KRaftMigrationDriver.this.image = image;
String metadataType = isSnapshot ? "snapshot" : "delta";
if (migrationState.equals(MigrationDriverState.INACTIVE)) {
// No need to log anything if this node is not the active controller
if (EnumSet.of(MigrationDriverState.UNINITIALIZED, MigrationDriverState.INACTIVE).contains(migrationState)) {
// No need to log anything if this node is not the active controller or the driver has not initialized
completionHandler.accept(null);
return;
}

26
metadata/src/test/java/org/apache/kafka/metadata/migration/KRaftMigrationDriverTest.java
View File

@ -232,6 +232,32 @@ public class KRaftMigrationDriverTest {
return future;
}
@Test
public void testOnControllerChangeWhenUninitialized() throws InterruptedException {
CountingMetadataPropagator metadataPropagator = new CountingMetadataPropagator();
CapturingMigrationClient.newBuilder().build();
CapturingMigrationClient migrationClient = CapturingMigrationClient.newBuilder().build();
MockFaultHandler faultHandler = new MockFaultHandler("testBecomeLeaderUninitialized");
KRaftMigrationDriver.Builder builder = defaultTestBuilder()
.setZkMigrationClient(migrationClient)
.setPropagator(metadataPropagator)
.setFaultHandler(faultHandler);
try (KRaftMigrationDriver driver = builder.build()) {
// Fake a complete migration with ZK client
migrationClient.setMigrationRecoveryState(
ZkMigrationLeadershipState.EMPTY.withKRaftMetadataOffsetAndEpoch(100, 1));
// simulate the Raft layer running before the driver has fully started.
driver.onControllerChange(new LeaderAndEpoch(OptionalInt.of(3000), 1));
// start up the driver. this will enqueue a poll event. once run, this will enqueue a recovery event
driver.start();
// Even though we contrived a race above, the driver still makes it past initialization.
TestUtils.waitForCondition(() -> driver.migrationState().get(30, TimeUnit.SECONDS).equals(MigrationDriverState.WAIT_FOR_CONTROLLER_QUORUM),
"Waiting for KRaftMigrationDriver to enter WAIT_FOR_CONTROLLER_QUORUM state");
}
}
/**
* Don't send RPCs to brokers for every metadata change, only when brokers or topics change.
* This is a regression test for KAFKA-14668