wcarlson5 commented on a change in pull request #9615:
URL: https://github.com/apache/kafka/pull/9615#discussion_r533707640
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File path: streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java
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@@ -894,19 +885,88 @@ private KafkaStreams(final InternalTopologyBuilder
internalTopologyBuilder,
queryableStoreProvider = new QueryableStoreProvider(storeProviders,
globalStateStoreProvider);
stateDirCleaner = setupStateDirCleaner();
- oldHandler = false;
maybeWarnAboutCodeInRocksDBConfigSetter(log, config);
rocksDBMetricsRecordingService =
maybeCreateRocksDBMetricsRecordingService(clientId, config);
}
+ private StreamThread createStreamThread(final long cacheSizePerThread,
final int threadIdx) {
+ final StreamThread streamThread = StreamThread.create(
+ internalTopologyBuilder,
+ config,
+ clientSupplier,
+ adminClient,
+ processId,
+ clientId,
+ streamsMetrics,
+ time,
+ streamsMetadataState,
+ cacheSizePerThread,
+ stateDirectory,
+ delegatingStateRestoreListener,
+ threadIdx,
+ KafkaStreams.this::closeToError,
+ streamsUncaughtExceptionHandler
+ );
+ threads.add(streamThread);
+ threadState.put(streamThread.getId(), streamThread.state());
+ storeProviders.add(new StreamThreadStateStoreProvider(streamThread));
+ return streamThread;
+ }
+
+ /**
+ * Adds and starts a stream thread in addition to the stream threads that
are already running in this
+ * Kafka Streams client.
+ *
+ * Since the number of stream threads increases, the sizes of the caches
in the new stream thread
+ * and the existing stream threads are adapted so that the sum of the
cache sizes over all stream
+ * threads does not exceed the total cache size specified in configuration
+ * {@code cache.max.bytes.buffering}.
+ *
+ * Stream threads can only be added if this Kafka Streams client is in
state RUNNING or REBALANCING.
+ *
+ * @return name of the added stream thread or empty if a new stream thread
could not be added
+ */
+ public Optional<String> addStreamThread() {
+ if (isRunningOrRebalancing()) {
+ final int threadIdx = getNextThreadIndex();
+ final long cacheSizePerThread =
getCacheSizePerThread(threads.size() + 1);
+ resizeThreadCache(cacheSizePerThread);
+ final StreamThread streamThread =
createStreamThread(cacheSizePerThread, threadIdx);
+ streamThread.setStateListener(streamStateListener);
+ synchronized (stateLock) {
+ if (isRunningOrRebalancing()) {
+ streamThread.start();
Review comment:
I think when a state transition is changed or add is when these changes
should be made. Removing from the thread list is low cost as is increasing the
size of the cache, so it won't be expensive to make these changes for all cases.
I think the two good options we have is that we can move the cache resize
and create thread into the stateLock or we can undo the changes we made if we
have to abort starting the new thread.
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