egor-ryashin commented on a change in pull request #6041: Synchronize scheduled poll() calls in SQLMetadataSegmentManager URL: https://github.com/apache/incubator-druid/pull/6041#discussion_r296711525
########## File path: server/src/main/java/io/druid/metadata/SQLMetadataSegmentManager.java ########## @@ -85,20 +85,38 @@ private static final Interner<DataSegment> DATA_SEGMENT_INTERNER = Interners.newWeakInterner(); private static final EmittingLogger log = new EmittingLogger(SQLMetadataSegmentManager.class); - // Use to synchronize start() and stop(). These methods should be synchronized to prevent from being called at the - // same time if two different threads are calling them. This might be possible if a druid coordinator gets and drops - // leadership repeatedly in quick succession. - private final Object lock = new Object(); + /** + * Use to synchronize {@link #start()}, {@link #stop()}, {@link #poll()}, and {@link #isStarted()}. These methods + * should be synchronized to prevent from being called at the same time if two different threads are calling them. + * This might be possible if a druid coordinator gets and drops leadership repeatedly in quick succession. + */ + private final ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock(); Review comment: I wonder if this should be the responsibility of the Lifecycle to synchronize start/stop of objects ? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org