Fixed deadlock on single thread executor

Author: alex268

topic/src/main/java/tech/ydb/topic/read/impl/AsyncReaderImpl.java

@@ -194,6 +194,6 @@ public CompletableFuture<Void> shutdown() {
     private void logUserThrowableAndStopWorking(Throwable th, String callbackName) {
         String errorMessage = "Unhandled throwable in " + callbackName + " user callback: " + th;
         logger.error(errorMessage);
-        shutdownImpl(errorMessage).join();
+        shutdownImpl(errorMessage);
     }
 }

topic/src/test/java/tech/ydb/topic/impl/TopicReadersIntegrationTest.java

@@ -0,0 +1,109 @@
+package tech.ydb.topic.impl;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import tech.ydb.core.Status;
+import tech.ydb.test.junit4.GrpcTransportRule;
+import tech.ydb.topic.TopicClient;
+import tech.ydb.topic.description.Consumer;
+import tech.ydb.topic.read.AsyncReader;
+import tech.ydb.topic.settings.CreateTopicSettings;
+import tech.ydb.topic.settings.ReadEventHandlersSettings;
+import tech.ydb.topic.settings.ReaderSettings;
+import tech.ydb.topic.settings.TopicReadSettings;
+import tech.ydb.topic.settings.WriterSettings;
+import tech.ydb.topic.write.Message;
+import tech.ydb.topic.write.SyncWriter;
+
+/**
+ *
+ * @author Aleksandr Gorshenin
+ */
+public class TopicReadersIntegrationTest {
+    private final static Logger logger = LoggerFactory.getLogger(YdbTopicsIntegrationTest.class);
+
+    @ClassRule
+    public final static GrpcTransportRule ydbTransport = new GrpcTransportRule();
+
+    private final static String TEST_TOPIC = "topic_readers_test";
+
+    private final static String TEST_CONSUMER1 = "consumer";
+
+    private static TopicClient client;
+
+    @BeforeClass
+    public static void initTopic() {
+        logger.info("Create test table  {} ...", TEST_TOPIC);
+
+        client = TopicClient.newClient(ydbTransport).build();
+        client.createTopic(TEST_TOPIC, CreateTopicSettings.newBuilder()
+                .addConsumer(Consumer.newBuilder().setName(TEST_CONSUMER1).build())
+                .build()
+        ).join().expectSuccess("can't create a new topic");
+    }
+
+    @AfterClass
+    public static void dropTopic() {
+        logger.info("Drop test topic {} ...", TEST_TOPIC);
+        Status dropStatus = client.dropTopic(TEST_TOPIC).join();
+        client.close();
+        dropStatus.expectSuccess("can't drop test topic");
+    }
+
+    private void sendMessages(Message... messages) throws Exception {
+        WriterSettings settings = WriterSettings.newBuilder()
+                .setTopicPath(TEST_TOPIC)
+                .setProducerId("helper")
+                .build();
+        SyncWriter writer = client.createSyncWriter(settings);
+        writer.initAndWait();
+        for (Message message : messages) {
+            writer.send(message);
+        }
+
+        writer.flush();
+        writer.shutdown(10, TimeUnit.SECONDS);
+    }
+
+    @Test
+    public void singleThreadExecutorTest() throws Exception {
+        ReaderSettings readerSettings = ReaderSettings.newBuilder()
+                .addTopic(TopicReadSettings.newBuilder()
+                        .setPath(TEST_TOPIC)
+                        .build())
+                .setConsumerName(TEST_CONSUMER1)
+                .build();
+
+        Semaphore messageCount = new Semaphore(0);
+
+        ExecutorService executor = Executors.newSingleThreadExecutor((r) -> new Thread(r, "test-executor"));
+        AsyncReader reader = client.createAsyncReader(readerSettings, ReadEventHandlersSettings.newBuilder()
+                .setExecutor(executor)
+                .setEventHandler((event) -> {
+                    messageCount.release();
+                    event.commit().join();
+                }).build()
+        );
+
+        reader.init().join();
+
+        sendMessages(Message.of("test".getBytes()));
+
+        // wait for message committing
+        messageCount.acquireUninterruptibly();
+
+        reader.shutdown().get(5, TimeUnit.SECONDS);
+
+        executor.shutdownNow();
+    }
+}