Let PoolUtilities use its own executor. Sharing executors can lead to deadlocks (not observed, but theoretical)

hikaricp-common/src/main/java/com/zaxxer/hikari/pool/BaseHikariPool.java

@@ -372,14 +372,14 @@ public abstract class BaseHikariPool implements HikariPoolMBean, IBagStateListen
 
          final boolean timeoutEnabled = (connectionTimeout != Integer.MAX_VALUE);
          final long timeoutMs = timeoutEnabled ? Math.max(250L, connectionTimeout) : 0L;
-         final int originalTimeout = poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, timeoutMs, timeoutEnabled);
+         final int originalTimeout = poolUtils.setNetworkTimeout(connection, timeoutMs, timeoutEnabled);
 
          transactionIsolation = (transactionIsolation < 0 ? connection.getTransactionIsolation() : transactionIsolation);
          
          poolUtils.setupConnection(connection, isAutoCommit, isReadOnly, transactionIsolation, catalog);
          connectionCustomizer.customize(connection);
          poolUtils.executeSql(connection, configuration.getConnectionInitSql(), isAutoCommit);
-         poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, originalTimeout, timeoutEnabled);
+         poolUtils.setNetworkTimeout(connection, originalTimeout, timeoutEnabled);
          
          connectionBag.add(new PoolBagEntry(connection, this));
          lastConnectionFailure.set(null);

hikaricp-common/src/main/java/com/zaxxer/hikari/util/PoolUtilities.java

@@ -8,7 +8,6 @@ import java.sql.SQLException;
 import java.sql.SQLFeatureNotSupportedException;
 import java.sql.Statement;
 import java.util.Properties;
-import java.util.concurrent.Executor;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
@@ -20,14 +19,15 @@ import com.zaxxer.hikari.HikariConfig;
 
 public final class PoolUtilities
 {
+   private final ThreadPoolExecutor executorService;
+
    private volatile boolean IS_JDBC40;
    private volatile boolean IS_JDBC41;
    private volatile boolean jdbc40checked; 
    private volatile boolean jdbc41checked; 
    private volatile boolean queryTimeoutSupported = true;
-   private volatile ThreadPoolExecutor executorService;
 
-   public PoolUtilities(HikariConfig configuration)
+   public PoolUtilities(final HikariConfig configuration)
    {
       executorService = createThreadPoolExecutor(configuration.getMaximumPoolSize(), "HikariCP utility thread (pool " + configuration.getPoolName() + ")", configuration.getThreadFactory(), new ThreadPoolExecutor.DiscardPolicy());
    }
@@ -42,7 +42,7 @@ public final class PoolUtilities
       if (connection != null) {
          try {
             try {
-               setNetworkTimeout(executorService, connection, TimeUnit.SECONDS.toMillis(30), true);
+               setNetworkTimeout(connection, TimeUnit.SECONDS.toMillis(30), true);
             }
             catch (SQLException e) {
                // keep going, close anyway
@@ -196,12 +196,12 @@ public final class PoolUtilities
     * @return the pre-existing network timeout value
     * @throws SQLException thrown if the network timeout cannot be set
     */
-   public int setNetworkTimeout(final Executor executor, final Connection connection, final long timeoutMs, final boolean isUseNetworkTimeout) throws SQLException
+   public int setNetworkTimeout(final Connection connection, final long timeoutMs, final boolean isUseNetworkTimeout) throws SQLException
    {
       if ((IS_JDBC41 || !jdbc41checked) && isUseNetworkTimeout) {
          try {
             final int networkTimeout = connection.getNetworkTimeout();
-            connection.setNetworkTimeout(executor, (int) timeoutMs);
+            connection.setNetworkTimeout(executorService, (int) timeoutMs);
             IS_JDBC41 = true;
             return networkTimeout;
          }

hikaricp-common/src/test/java/com/zaxxer/hikari/StatementTest.java

@@ -9,8 +9,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import com.zaxxer.hikari.util.UtilityElf;
-
 public class StatementTest
 {
     private HikariDataSource ds;

hikaricp-java6/src/main/java/com/zaxxer/hikari/pool/HikariPool.java

@@ -160,7 +160,7 @@ public final class HikariPool extends BaseHikariPool
             return connection.isValid(timeoutSec);
          }
 
-         final int networkTimeout = poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, Math.max(1000, (int) timeoutMs), timeoutEnabled);
+         final int networkTimeout = poolUtils.setNetworkTimeout(connection, Math.max(1000, (int) timeoutMs), timeoutEnabled);
 
          Statement statement = connection.createStatement();
          try {
@@ -175,7 +175,7 @@ public final class HikariPool extends BaseHikariPool
             connection.rollback();
          }
 
-         poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, networkTimeout, timeoutEnabled);
+         poolUtils.setNetworkTimeout(connection, networkTimeout, timeoutEnabled);
 
          return true;
       }

hikaricp/src/main/java/com/zaxxer/hikari/pool/HikariPool.java

@@ -144,7 +144,7 @@ public final class HikariPool extends BaseHikariPool
             return connection.isValid(timeoutSec);
          }
 
-         final int networkTimeout = poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, Math.max(1000, (int) timeoutMs), timeoutEnabled);
+         final int networkTimeout = poolUtils.setNetworkTimeout(connection, Math.max(1000, (int) timeoutMs), timeoutEnabled);
 
          try (Statement statement = connection.createStatement()) {
             poolUtils.setQueryTimeout(statement, timeoutSec);
@@ -155,7 +155,7 @@ public final class HikariPool extends BaseHikariPool
             connection.rollback();
          }
 
-         poolUtils.setNetworkTimeout(houseKeepingExecutorService, connection, networkTimeout, timeoutEnabled);
+         poolUtils.setNetworkTimeout(connection, networkTimeout, timeoutEnabled);
 
          return true;
       }