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Posted to jira@kafka.apache.org by GitBox <gi...@apache.org> on 2020/11/19 18:17:10 UTC

[GitHub] [kafka] wcarlson5 commented on a change in pull request #9615: KAFKA-10500: Add thread option

wcarlson5 commented on a change in pull request #9615:
URL: https://github.com/apache/kafka/pull/9615#discussion_r527099742



##########
File path: streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java
##########
@@ -894,11 +904,57 @@ private KafkaStreams(final InternalTopologyBuilder internalTopologyBuilder,
         queryableStoreProvider = new QueryableStoreProvider(storeProviders, globalStateStoreProvider);
 
         stateDirCleaner = setupStateDirCleaner();
-        oldHandler = false;
         maybeWarnAboutCodeInRocksDBConfigSetter(log, config);
         rocksDBMetricsRecordingService = maybeCreateRocksDBMetricsRecordingService(clientId, config);
     }
 
+    /**
+     * 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() {
+        synchronized (stateLock) {
+            if (state == State.RUNNING || state == State.REBALANCING) {
+                final int threadIdx = threads.size() + 1;

Review comment:
       Looks like I didn't understand threadIdx. that makes sense now

##########
File path: streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java
##########
@@ -894,11 +904,57 @@ private KafkaStreams(final InternalTopologyBuilder internalTopologyBuilder,
         queryableStoreProvider = new QueryableStoreProvider(storeProviders, globalStateStoreProvider);
 
         stateDirCleaner = setupStateDirCleaner();
-        oldHandler = false;
         maybeWarnAboutCodeInRocksDBConfigSetter(log, config);
         rocksDBMetricsRecordingService = maybeCreateRocksDBMetricsRecordingService(clientId, config);
     }
 
+    /**
+     * 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() {
+        synchronized (stateLock) {
+            if (state == State.RUNNING || state == State.REBALANCING) {
+                final int threadIdx = threads.size() + 1;
+                final long cacheSizePerThread = getCacheSizePerThread(threadIdx);
+                resizeThreadCache(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));
+                streamThread.setStateListener(streamStateListener);
+                return Optional.of(streamThread.getName());
+            } else {
+                return Optional.empty();
+            }
+        }
+    }

Review comment:
       right before the positive return




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