cached thread pool

Author: Neenu1995

java-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryConnection.java

@@ -349,8 +349,8 @@ public class BigQueryConnection extends BigQueryNoOpsConnection {
 
       this.headerProvider = createHeaderProvider();
       this.bigQuery = getBigQueryConnection();
-      this.metadataExecutor = BigQueryJdbcMdc.newFixedThreadPool(this.metadataFetchThreadCount);
-      this.queryExecutor = BigQueryJdbcMdc.newFixedThreadPool(this.queryExecutionThreadCount);
+      this.metadataExecutor = BigQueryJdbcMdc.newCachedThreadPool();
+      this.queryExecutor = BigQueryJdbcMdc.newCachedThreadPool();
     }
   }
 

java-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryJdbcMdc.java

@@ -77,6 +77,28 @@ static ExecutorService newFixedThreadPool(int nThreads) {
     return newFixedThreadPool(nThreads, Executors.defaultThreadFactory());
   }
 
+  /**
+   * Creates a new cached thread pool ExecutorService that automatically propagates MDC connection
+   * context from the submitting thread to the executing thread.
+   */
+  static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
+    return new MdcThreadPoolExecutor(
+        0,
+        Integer.MAX_VALUE,
+        60L,
+        TimeUnit.SECONDS,
+        new java.util.concurrent.SynchronousQueue<>(),
+        new MdcThreadFactory(threadFactory));
+  }
+
+  /**
+   * Creates a new cached thread pool ExecutorService that automatically propagates MDC connection
+   * context from the submitting thread to the executing thread.
+   */
+  static ExecutorService newCachedThreadPool() {
+    return newCachedThreadPool(Executors.defaultThreadFactory());
+  }
+
   private static class MdcThreadFactory implements ThreadFactory {
     private final ThreadFactory delegate;
 

java-bigquery-jdbc/src/test/java/com/google/cloud/bigquery/jdbc/BigQueryJdbcMdcTest.java

@@ -281,10 +281,14 @@ public void testConnectionScopedExecutorLifecycle() throws Exception {
       assertTrue(metadataExec1 instanceof ThreadPoolExecutor);
       assertTrue(metadataExec2 instanceof ThreadPoolExecutor);
 
-      assertEquals(6, ((ThreadPoolExecutor) exec1).getCorePoolSize());
-      assertEquals(12, ((ThreadPoolExecutor) exec2).getCorePoolSize());
-      assertEquals(5, ((ThreadPoolExecutor) metadataExec1).getCorePoolSize());
-      assertEquals(10, ((ThreadPoolExecutor) metadataExec2).getCorePoolSize());
+      assertEquals(0, ((ThreadPoolExecutor) exec1).getCorePoolSize());
+      assertEquals(Integer.MAX_VALUE, ((ThreadPoolExecutor) exec1).getMaximumPoolSize());
+      assertEquals(0, ((ThreadPoolExecutor) exec2).getCorePoolSize());
+      assertEquals(Integer.MAX_VALUE, ((ThreadPoolExecutor) exec2).getMaximumPoolSize());
+      assertEquals(0, ((ThreadPoolExecutor) metadataExec1).getCorePoolSize());
+      assertEquals(Integer.MAX_VALUE, ((ThreadPoolExecutor) metadataExec1).getMaximumPoolSize());
+      assertEquals(0, ((ThreadPoolExecutor) metadataExec2).getCorePoolSize());
+      assertEquals(Integer.MAX_VALUE, ((ThreadPoolExecutor) metadataExec2).getMaximumPoolSize());
 
       try (BigQueryJdbcMdc.MdcCloseable mdc =
           BigQueryJdbcMdc.registerInstance(conn1.getConnectionId())) {