diff --git a/README.md b/README.md
index 92c14efb..31978b6b 100644
--- a/README.md
+++ b/README.md
@@ -378,11 +378,11 @@ Here is a list of JDBC *DataSource* classes for popular databases:
 | Firebird         | Jaybird      | org.firebirdsql.pool.FBSimpleDataSource |
 | H2               | H2           | org.h2.jdbcx.JdbcDataSource |
 | HSQLDB           | HSQLDB       | org.hsqldb.jdbc.JDBCDataSource |
-| IBM AS400        | IBM          | com.ibm.as400.access.AS400JDBCDriver |
-| IBM DB2          | DB2          | com.ibm.db2.jcc.DB2SimpleDataSource |
-| MariaDB & MySQL  | MariaDB      | org.mariadb.jdbc.MySQLDataSource |
-| MySQL            | Connector/J  | com.mysql.jdbc.jdbc2.optional.MysqlDataSource |
+| IBM DB2          | IBM JCC      | com.ibm.db2.jcc.DB2SimpleDataSource |
+| IBM Informix     | IBM Informix | com.informix.jdbcx.IfxDataSource |
 | MS SQL Server    | Microsoft    | com.microsoft.sqlserver.jdbc.SQLServerDataSource |
+| MySQL            | Connector/J  | com.mysql.jdbc.jdbc2.optional.MysqlDataSource |
+| MySQL/MariaDB    | MariaDB      | org.mariadb.jdbc.MySQLDataSource |
 | Oracle           | Oracle       | oracle.jdbc.pool.OracleDataSource |
 | OrientDB         | OrientDB     | com.orientechnologies.orient.jdbc.OrientDataSource |
 | PostgreSQL       | pgjdbc-ng    | com.impossibl.postgres.jdbc.PGDataSource |
diff --git a/src/main/java/com/zaxxer/hikari/HikariConfig.java b/src/main/java/com/zaxxer/hikari/HikariConfig.java
index 98dbb565..be618cd6 100644
--- a/src/main/java/com/zaxxer/hikari/HikariConfig.java
+++ b/src/main/java/com/zaxxer/hikari/HikariConfig.java
@@ -116,14 +116,15 @@ public class HikariConfig implements HikariConfigMXBean
       dataSourceProperties = new Properties();
       healthCheckProperties = new Properties();
 
+      minIdle = -1;
+      maxPoolSize = -1;
+      maxLifetime = MAX_LIFETIME;
       connectionTimeout = CONNECTION_TIMEOUT;
       validationTimeout = VALIDATION_TIMEOUT;
       idleTimeout = IDLE_TIMEOUT;
+
       isAutoCommit = true;
       isInitializationFailFast = true;
-      minIdle = -1;
-      maxPoolSize = 10;
-      maxLifetime = MAX_LIFETIME;
 
       String systemProp = System.getProperty("hikaricp.configurationFile");
       if ( systemProp != null) {
@@ -775,8 +776,7 @@ public class HikariConfig implements HikariConfigMXBean
       if (poolName == null) {
          poolName = "HikariPool-" + POOL_NUMBER.getAndIncrement();
       }
-
-      if (poolName.contains(":") && isRegisterMbeans) {
+      else if (isRegisterMbeans && poolName.contains(":")) {
          throw new IllegalArgumentException("poolName cannot contain ':' when used with JMX");
       }
 
@@ -828,8 +828,7 @@ public class HikariConfig implements HikariConfigMXBean
       }
 
       if (idleTimeout + TimeUnit.SECONDS.toMillis(1) > maxLifetime && maxLifetime > 0) {
-         LOGGER.warn("idleTimeout is close to or greater than maxLifetime, disabling it.");
-         maxLifetime = idleTimeout;
+         LOGGER.warn("idleTimeout is close to or more than maxLifetime, disabling it.");
          idleTimeout = 0;
       }
 
@@ -838,29 +837,33 @@ public class HikariConfig implements HikariConfigMXBean
          idleTimeout = IDLE_TIMEOUT;
       }
 
-      if (leakDetectionThreshold != 0 && leakDetectionThreshold < TimeUnit.SECONDS.toMillis(2) && !unitTest) {
-         LOGGER.warn("leakDetectionThreshold is less than 2000ms, setting to minimum 2000ms.");
-         leakDetectionThreshold = 2000L;
+      if (leakDetectionThreshold > 0 && !unitTest) {
+         if (leakDetectionThreshold < TimeUnit.SECONDS.toMillis(2) || (leakDetectionThreshold > maxLifetime && maxLifetime > 0)) {        
+            LOGGER.warn("leakDetectionThreshold is less than 2000ms or more than maxLifetime, disabling it.");
+            leakDetectionThreshold = 0L;
+         }
       }
 
       if (connectionTimeout != Integer.MAX_VALUE) {
          if (validationTimeout > connectionTimeout) {
-            LOGGER.warn("validationTimeout should be less than connectionTimeout, setting validationTimeout to connectionTimeout");
+            LOGGER.warn("validationTimeout should be less than connectionTimeout, setting validationTimeout to connectionTimeout.");
             validationTimeout = connectionTimeout;
          }
          if (maxLifetime > 0 && connectionTimeout > maxLifetime) {
-            LOGGER.warn("connectionTimeout should be less than maxLifetime, setting maxLifetime to connectionTimeout");
-            maxLifetime = connectionTimeout;
+            LOGGER.warn("connectionTimeout should be less than maxLifetime, setting connectionTimeout to maxLifetime.");
+            connectionTimeout = maxLifetime;
          }
       }
 
-      if (minIdle < 0) {
-         minIdle = maxPoolSize;
-      }
-      else if (minIdle > maxPoolSize) {
-         LOGGER.warn("minIdle should be less than maxPoolSize, setting maxPoolSize to minIdle");
+      if (maxPoolSize < 0) {
+         if (minIdle < 0) {
+            minIdle = 10;
+         }
          maxPoolSize = minIdle;
       }
+      else if (minIdle < 0 || minIdle > maxPoolSize) {
+         minIdle = maxPoolSize;
+      }
    }
 
    private void logConfiguration()
diff --git a/src/main/java/com/zaxxer/hikari/HikariJNDIFactory.java b/src/main/java/com/zaxxer/hikari/HikariJNDIFactory.java
index a3c09a18..51360289 100644
--- a/src/main/java/com/zaxxer/hikari/HikariJNDIFactory.java
+++ b/src/main/java/com/zaxxer/hikari/HikariJNDIFactory.java
@@ -40,7 +40,7 @@ import com.zaxxer.hikari.util.PropertyElf;
 public class HikariJNDIFactory implements ObjectFactory
 {
    @Override
-   public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable<?, ?> environment) throws Exception
+   synchronized public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable<?, ?> environment) throws Exception
    {
       // We only know how to deal with <code>javax.naming.Reference</code> that specify a class name of "javax.sql.DataSource"
       if (!(obj instanceof Reference)) {
@@ -67,27 +67,27 @@ public class HikariJNDIFactory implements ObjectFactory
       return createDataSource(properties, nameCtx);
    }
 
-   private DataSource createDataSource(Properties properties, Context context) throws NamingException
+   private DataSource createDataSource(final Properties properties, final Context context) throws NamingException
    {
-      if (properties.getProperty("dataSourceJNDI") != null) {
-         return lookupJndiDataSource(properties, context);
+      String jndiName = properties.getProperty("dataSourceJNDI");
+      if (jndiName != null) {
+         return lookupJndiDataSource(properties, context, jndiName);
       }
 
       return new HikariDataSource(new HikariConfig(properties));
    }
 
-   private DataSource lookupJndiDataSource(Properties properties, Context context) throws NamingException
+   private DataSource lookupJndiDataSource(final Properties properties, final Context context, final String jndiName) throws NamingException
    {
       if (context == null) {
-         throw new RuntimeException("dataSourceJNDI property is configured, but local JNDI context is null.");
+         throw new RuntimeException("JNDI context does not found for dataSourceJNDI : " + jndiName);
       }
 
-      String jndiName = properties.getProperty("dataSourceJNDI");
       DataSource jndiDS = (DataSource) context.lookup(jndiName);
       if (jndiDS == null) {
-         context = new InitialContext();
-         jndiDS = (DataSource) context.lookup(jndiName);
-         context.close();
+         final Context ic = new InitialContext();
+         jndiDS = (DataSource) ic.lookup(jndiName);
+         ic.close();
       }
 
       if (jndiDS != null) {
diff --git a/src/main/java/com/zaxxer/hikari/pool/HikariPool.java b/src/main/java/com/zaxxer/hikari/pool/HikariPool.java
index 54314848..d0906e17 100644
--- a/src/main/java/com/zaxxer/hikari/pool/HikariPool.java
+++ b/src/main/java/com/zaxxer/hikari/pool/HikariPool.java
@@ -45,7 +45,7 @@ import com.zaxxer.hikari.metrics.dropwizard.CodahaleMetricsTrackerFactory;
 import com.zaxxer.hikari.util.ClockSource;
 import com.zaxxer.hikari.util.ConcurrentBag;
 import com.zaxxer.hikari.util.ConcurrentBag.IBagStateListener;
-import com.zaxxer.hikari.util.DefaultThreadFactory;
+import com.zaxxer.hikari.util.UtilityElf.DefaultThreadFactory;
 import com.zaxxer.hikari.util.SuspendResumeLock;
 
 import static com.zaxxer.hikari.pool.PoolEntry.LASTACCESS_COMPARABLE;
@@ -67,17 +67,16 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
 
    private static final ClockSource clockSource = ClockSource.INSTANCE;
 
-   private final long ALIVE_BYPASS_WINDOW_MS = Long.getLong("com.zaxxer.hikari.aliveBypassWindowMs", TimeUnit.MILLISECONDS.toMillis(500));
-   private final long HOUSEKEEPING_PERIOD_MS = Long.getLong("com.zaxxer.hikari.housekeeping.periodMs", TimeUnit.SECONDS.toMillis(30));
-
-   private final PoolEntryCreator POOL_ENTRY_CREATOR = new PoolEntryCreator();
-
    private static final int POOL_NORMAL = 0;
    private static final int POOL_SUSPENDED = 1;
    private static final int POOL_SHUTDOWN = 2;
 
    private volatile int poolState;
 
+   private final long ALIVE_BYPASS_WINDOW_MS = Long.getLong("com.zaxxer.hikari.aliveBypassWindowMs", TimeUnit.MILLISECONDS.toMillis(500));
+   private final long HOUSEKEEPING_PERIOD_MS = Long.getLong("com.zaxxer.hikari.housekeeping.periodMs", TimeUnit.SECONDS.toMillis(30));
+
+   private final PoolEntryCreator POOL_ENTRY_CREATOR = new PoolEntryCreator();
    private final AtomicInteger totalConnections;
    private final ThreadPoolExecutor addConnectionExecutor;
    private final ThreadPoolExecutor closeConnectionExecutor;
@@ -89,7 +88,6 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
    private final SuspendResumeLock suspendResumeLock;
 
    private MetricsTrackerDelegate metricsTracker;
-   private boolean isRecordMetrics;
 
    /**
     * Construct a HikariPool with the specified configuration.
@@ -104,9 +102,6 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
       this.totalConnections = new AtomicInteger();
       this.suspendResumeLock = config.isAllowPoolSuspension() ? new SuspendResumeLock() : SuspendResumeLock.FAUX_LOCK;
 
-      this.addConnectionExecutor = createThreadPoolExecutor(config.getMaximumPoolSize(), "Hikari connection adder (pool " + poolName + ")", config.getThreadFactory(), new ThreadPoolExecutor.DiscardPolicy());
-      this.closeConnectionExecutor = createThreadPoolExecutor(1 + (config.getMaximumPoolSize() / 2), "Hikari connection closer (pool " + poolName + ")", config.getThreadFactory(), new ThreadPoolExecutor.CallerRunsPolicy());
-
       if (config.getMetricsTrackerFactory() != null) {
          setMetricsTrackerFactory(config.getMetricsTrackerFactory());
       }
@@ -120,8 +115,12 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
 
       checkFailFast();
 
+      ThreadFactory threadFactory = config.getThreadFactory();
+      this.addConnectionExecutor = createThreadPoolExecutor(config.getMaximumPoolSize(), "Hikari connection adder (pool " + poolName + ")", threadFactory, new ThreadPoolExecutor.DiscardPolicy());
+      this.closeConnectionExecutor = createThreadPoolExecutor(1 + (config.getMaximumPoolSize() / 2), "Hikari connection closer (pool " + poolName + ")", threadFactory, new ThreadPoolExecutor.CallerRunsPolicy());
+
       if (config.getScheduledExecutorService() == null) {
-         ThreadFactory threadFactory = config.getThreadFactory() != null ? config.getThreadFactory() : new DefaultThreadFactory("Hikari housekeeper (pool " + poolName + ")", true);
+         threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory("Hikari housekeeper (pool " + poolName + ")", true);
          this.houseKeepingExecutorService = new ScheduledThreadPoolExecutor(1, threadFactory, new ThreadPoolExecutor.DiscardPolicy());
          this.houseKeepingExecutorService.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
          this.houseKeepingExecutorService.setRemoveOnCancelPolicy(true);
@@ -265,8 +264,7 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
 
    public void setMetricRegistry(Object metricRegistry)
    {
-      this.isRecordMetrics = metricRegistry != null;
-      if (isRecordMetrics) {
+      if (metricRegistry != null) {
          setMetricsTrackerFactory(new CodahaleMetricsTrackerFactory((MetricRegistry) metricRegistry));
       }
       else {
@@ -276,8 +274,7 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
 
    public void setMetricsTrackerFactory(MetricsTrackerFactory metricsTrackerFactory)
    {
-      this.isRecordMetrics = metricsTrackerFactory != null;
-      if (isRecordMetrics) {
+      if (metricsTrackerFactory != null) {
          this.metricsTracker = new MetricsTrackerDelegate(metricsTrackerFactory.create(config.getPoolName(), getPoolStats()));
       }
       else {
@@ -407,13 +404,11 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
    final void closeConnection(final PoolEntry poolEntry, final String closureReason)
    {
       if (connectionBag.remove(poolEntry)) {
-         final Connection connection = poolEntry.connection;
-         poolEntry.close();
          final int tc = totalConnections.decrementAndGet();
          if (tc < 0) {
-            LOGGER.warn("{} - Internal accounting inconsistency, totalConnections={}", poolName, tc, new Exception());
+            LOGGER.warn("{} - Unexpected value of totalConnections={}", poolName, tc, new Exception());
          }
-
+         final Connection connection = poolEntry.close();
          closeConnectionExecutor.execute(new Runnable() {
             @Override
             public void run() {
@@ -588,8 +583,8 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
          validationTimeout = config.getValidationTimeout();
          leakTask.updateLeakDetectionThreshold(config.getLeakDetectionThreshold());
 
-         final long now = clockSource.currentTime();
          final long idleTimeout = config.getIdleTimeout();
+         final long now = clockSource.currentTime();
 
          // Detect retrograde time, allowing +128ms as per NTP spec.
          if (clockSource.plusMillis(now, 128) < clockSource.plusMillis(previous, HOUSEKEEPING_PERIOD_MS)) {
diff --git a/src/main/java/com/zaxxer/hikari/pool/PoolBase.java b/src/main/java/com/zaxxer/hikari/pool/PoolBase.java
index d0de7ebf..0dab0642 100644
--- a/src/main/java/com/zaxxer/hikari/pool/PoolBase.java
+++ b/src/main/java/com/zaxxer/hikari/pool/PoolBase.java
@@ -29,10 +29,10 @@ import org.slf4j.LoggerFactory;
 import com.zaxxer.hikari.HikariConfig;
 import com.zaxxer.hikari.metrics.MetricsTracker;
 import com.zaxxer.hikari.util.ClockSource;
-import com.zaxxer.hikari.util.DefaultThreadFactory;
 import com.zaxxer.hikari.util.DriverDataSource;
 import com.zaxxer.hikari.util.PropertyElf;
 import com.zaxxer.hikari.util.UtilityElf;
+import com.zaxxer.hikari.util.UtilityElf.DefaultThreadFactory;
 
 abstract class PoolBase
 {
@@ -48,15 +48,17 @@ abstract class PoolBase
    private static final int FALSE = 0;
 
    private int networkTimeout;
-   private int transactionIsolation;
    private int isNetworkTimeoutSupported;
    private int isQueryTimeoutSupported;
+   private int defaultTransactionIsolation;
+   private int transactionIsolation;
    private Executor netTimeoutExecutor;
    private DataSource dataSource;
 
    private final String catalog;
    private final boolean isReadOnly;
    private final boolean isAutoCommit;
+
    private final boolean isUseJdbc4Validation;
    private final boolean isIsolateInternalQueries;
    private final AtomicReference<Throwable> lastConnectionFailure;
@@ -144,7 +146,7 @@ abstract class PoolBase
       }
       catch (SQLException e) {
          lastConnectionFailure.set(e);
-         LOGGER.warn("{} - Connection {} failed alive test with exception {}", poolName, connection, e.getMessage());
+         LOGGER.warn("{} - Failed to validate connection {} ({})", poolName, connection, e.getMessage());
          return false;
       }
    }
@@ -330,16 +332,12 @@ abstract class PoolBase
    {
       networkTimeout = getAndSetNetworkTimeout(connection, connectionTimeout);
 
-      checkValidationMode(connection);
+      checkDriverSupport(connection);
 
-      connection.setAutoCommit(isAutoCommit);
       connection.setReadOnly(isReadOnly);
+      connection.setAutoCommit(isAutoCommit);
 
-      final int defaultLevel = connection.getTransactionIsolation();
-      transactionIsolation = (transactionIsolation < 0 || defaultLevel == Connection.TRANSACTION_NONE)
-                           ? defaultLevel
-                           : transactionIsolation;
-      if (transactionIsolation != defaultLevel) {
+      if (transactionIsolation != defaultTransactionIsolation) {
          connection.setTransactionIsolation(transactionIsolation);
       }
 
@@ -357,7 +355,7 @@ abstract class PoolBase
     *
     * @param connection a Connection to check
     */
-   private void checkValidationMode(final Connection connection) throws SQLException
+   private void checkDriverSupport(final Connection connection) throws SQLException
    {
       if (!isValidChecked) {
          if (isUseJdbc4Validation) {
@@ -365,7 +363,7 @@ abstract class PoolBase
                connection.isValid(1);
             }
             catch (Throwable e) {
-               LOGGER.debug("{} - Connection.isValid() is not supported, configure connection test query. ({})", poolName, e.getMessage());
+               LOGGER.warn("{} - Failed to execute isValid() for connection, configure connection test query. ({})", poolName, e.getMessage());
                throw e;
             }
          }
@@ -374,10 +372,14 @@ abstract class PoolBase
                executeSql(connection, config.getConnectionTestQuery(), false, isIsolateInternalQueries && !isAutoCommit);
             }
             catch (Throwable e) {
-               LOGGER.debug("{} - Failed to execute connection test query. ({})", poolName, e.getMessage());
+               LOGGER.warn("{} - Failed to execute connection test query. ({})", poolName, e.getMessage());
                throw e;
             }
          }
+         defaultTransactionIsolation = connection.getTransactionIsolation();
+         if (transactionIsolation == -1) {
+            transactionIsolation = defaultTransactionIsolation;
+         }
          isValidChecked = true;
       }
    }
@@ -398,7 +400,7 @@ abstract class PoolBase
          catch (Throwable e) {
             if (isQueryTimeoutSupported == UNINITIALIZED) {
                isQueryTimeoutSupported = FALSE;
-               LOGGER.debug("{} - Statement.setQueryTimeout() is not supported ({})", poolName, e.getMessage());
+               LOGGER.warn("{} - Unable to set query timeout for statement. ({})", poolName, e.getMessage());
             }
          }
       }
@@ -424,7 +426,7 @@ abstract class PoolBase
          catch (Throwable e) {
             if (isNetworkTimeoutSupported == UNINITIALIZED) {
                isNetworkTimeoutSupported = FALSE;
-               LOGGER.debug("{} - Connection.setNetworkTimeout() is not supported ({})", poolName, e.getMessage());
+               LOGGER.warn("{} - Unable to get/set network timeout for connection. ({})", poolName, e.getMessage());
             }
          }
       }
@@ -459,17 +461,15 @@ abstract class PoolBase
    {
       if (sql != null) {
          try (Statement statement = connection.createStatement()) {
-
             //con created few ms before, set query timeout is omitted
             statement.execute(sql);
-
-            if (!isReadOnly) {
-               if (isCommit) {
-                  connection.commit();
-               }
-               else if (isRollback) {
-                  connection.rollback();
-               }
+         }
+         if (!isReadOnly) {
+            if (isCommit) {
+               connection.commit();
+            }
+            else if (isRollback) {
+               connection.rollback();
             }
          }
       }
@@ -484,7 +484,8 @@ abstract class PoolBase
          netTimeoutExecutor = new SynchronousExecutor();
       }
       else {
-         ThreadFactory threadFactory = config.getThreadFactory() != null ? config.getThreadFactory() : new DefaultThreadFactory("Hikari JDBC-timeout executor", true);
+         ThreadFactory threadFactory = config.getThreadFactory();
+         threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory("Hikari JDBC-timeout executor", true);
          ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newCachedThreadPool(threadFactory);
          executor.allowCoreThreadTimeOut(true);
          executor.setKeepAliveTime(15, TimeUnit.SECONDS);
@@ -502,7 +503,7 @@ abstract class PoolBase
             command.run();
          }
          catch (Throwable t) {
-            LoggerFactory.getLogger(PoolBase.class).debug("Exception executing {}", command, t);
+            LoggerFactory.getLogger(PoolBase.class).debug("Failed to execute: {}", command, t);
          }
       }
    }
@@ -520,7 +521,7 @@ abstract class PoolBase
             dataSource.setLoginTimeout((int) TimeUnit.MILLISECONDS.toSeconds(Math.max(1000L, connectionTimeout)));
          }
          catch (Throwable e) {
-            LOGGER.warn("{} - Unable to set DataSource login timeout", poolName, e);
+            LOGGER.warn("{} - Unable to set login timeout for data source. ({})", poolName, e.getMessage());
          }
       }
    }
diff --git a/src/main/java/com/zaxxer/hikari/pool/PoolEntry.java b/src/main/java/com/zaxxer/hikari/pool/PoolEntry.java
index f85d4693..6cb82e25 100644
--- a/src/main/java/com/zaxxer/hikari/pool/PoolEntry.java
+++ b/src/main/java/com/zaxxer/hikari/pool/PoolEntry.java
@@ -166,14 +166,16 @@ final class PoolEntry implements IConcurrentBagEntry
       state.lazySet(update);
    }
 
-   void close()
+   Connection close()
    {
       if (endOfLife != null && !endOfLife.isDone() && !endOfLife.cancel(false)) {
          LOGGER.warn("{} - maxLifeTime expiration task cancellation unexpectedly returned false for connection {}", getPoolName(), connection);
       }
 
-      endOfLife = null;
+      Connection con = connection;
       connection = null;
+      endOfLife = null;
+      return con;
    }
 
    private String stateToString()
diff --git a/src/main/java/com/zaxxer/hikari/util/DefaultThreadFactory.java b/src/main/java/com/zaxxer/hikari/util/DefaultThreadFactory.java
deleted file mode 100644
index 2db11b3a..00000000
--- a/src/main/java/com/zaxxer/hikari/util/DefaultThreadFactory.java
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- * Copyright (C) 2013, 2014 Brett Wooldridge
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.zaxxer.hikari.util;
-
-import java.util.concurrent.ThreadFactory;
-
-public class DefaultThreadFactory implements ThreadFactory {
-
-   private final String threadName;
-   private final boolean daemon;
-
-   public DefaultThreadFactory(String threadName, boolean daemon) {
-      this.threadName = threadName;
-      this.daemon = daemon;
-   }
-
-   @Override
-   public Thread newThread(Runnable r) {
-      Thread thread = new Thread(r, threadName);
-      thread.setDaemon(daemon);
-      return thread;
-   }
-}
diff --git a/src/main/java/com/zaxxer/hikari/util/UtilityElf.java b/src/main/java/com/zaxxer/hikari/util/UtilityElf.java
index b9d8a7b5..6e828eb5 100644
--- a/src/main/java/com/zaxxer/hikari/util/UtilityElf.java
+++ b/src/main/java/com/zaxxer/hikari/util/UtilityElf.java
@@ -73,18 +73,16 @@ public final class UtilityElf
 
       try {
          Class<?> loaded = UtilityElf.class.getClassLoader().loadClass(className);
+         if (args.length == 0) {
+            return clazz.cast(loaded.newInstance());
+         }
 
          Class<?>[] argClasses = new Class<?>[args.length];
          for (int i = 0; i < args.length; i++) {
             argClasses[i] = args[i].getClass();
          }
-
-         if (args.length > 0) {
-            Constructor<?> constructor = loaded.getConstructor(argClasses);
-            return clazz.cast(constructor.newInstance(args));
-         }
-
-         return clazz.cast(loaded.newInstance());
+         Constructor<?> constructor = loaded.getConstructor(argClasses);
+         return clazz.cast(constructor.newInstance(args));
       }
       catch (Exception e) {
          throw new RuntimeException(e);
@@ -150,4 +148,22 @@ public final class UtilityElf
 
       return -1;
    }
+
+   public static final class DefaultThreadFactory implements ThreadFactory {
+
+      private final String threadName;
+      private final boolean daemon;
+
+      public DefaultThreadFactory(String threadName, boolean daemon) {
+         this.threadName = threadName;
+         this.daemon = daemon;
+      }
+
+      @Override
+      public Thread newThread(Runnable r) {
+         Thread thread = new Thread(r, threadName);
+         thread.setDaemon(daemon);
+         return thread;
+      }
+   }
 }
diff --git a/src/test/java/com/zaxxer/hikari/pool/TestJNDI.java b/src/test/java/com/zaxxer/hikari/pool/TestJNDI.java
index 280810bf..404c9312 100644
--- a/src/test/java/com/zaxxer/hikari/pool/TestJNDI.java
+++ b/src/test/java/com/zaxxer/hikari/pool/TestJNDI.java
@@ -46,9 +46,10 @@ public class TestJNDI
       ref.add(new BogusRef("dataSource.loginTimeout", "10"));
       Context nameCtx = new BogusContext();
 
-      HikariDataSource ds = (HikariDataSource) jndi.getObjectInstance(ref, null, nameCtx, null);
-      Assert.assertNotNull(ds);
-      Assert.assertEquals("foo", ds.getUsername());
+      try (HikariDataSource ds = (HikariDataSource) jndi.getObjectInstance(ref, null, nameCtx, null)) {
+         Assert.assertNotNull(ds);
+         Assert.assertEquals("foo", ds.getUsername());
+      }
    }
 
    @Test
@@ -67,9 +68,10 @@ public class TestJNDI
       ref.add(new BogusRef("dataSource.loginTimeout", "10"));
       Context nameCtx = new BogusContext2();
 
-      HikariDataSource ds = (HikariDataSource) jndi.getObjectInstance(ref, null, nameCtx, null);
-      Assert.assertNotNull(ds);
-      Assert.assertEquals("foo", ds.getUsername());
+      try (HikariDataSource ds = (HikariDataSource) jndi.getObjectInstance(ref, null, nameCtx, null)) {
+         Assert.assertNotNull(ds);
+         Assert.assertEquals("foo", ds.getUsername());
+      }
    }
 
    @Test
@@ -84,7 +86,7 @@ public class TestJNDI
          Assert.fail();
       }
       catch (RuntimeException e) {
-         Assert.assertTrue(e.getMessage().contains("JNDI context is null"));
+         Assert.assertTrue(e.getMessage().contains("JNDI context does not found"));
       }
    }
 
diff --git a/src/test/java/com/zaxxer/hikari/pool/TestValidation.java b/src/test/java/com/zaxxer/hikari/pool/TestValidation.java
index f5214f8b..2642dd99 100644
--- a/src/test/java/com/zaxxer/hikari/pool/TestValidation.java
+++ b/src/test/java/com/zaxxer/hikari/pool/TestValidation.java
@@ -159,7 +159,7 @@ public class TestValidation
       config.validate();
 
       String s = new String(baos.toByteArray());
-      Assert.assertTrue("Expected exception to contain 'greater than maxLifetime' but contains *" + s + "*", s.contains("greater than maxLifetime"));
+      Assert.assertTrue("idleTimeout is close to or more than maxLifetime, disabling it." + s + "*", s.contains("is close to or more than maxLifetime"));
    }
 
    @Test
@@ -208,16 +208,11 @@ public class TestValidation
    @Test
    public void validateInvalidLeakDetection()
    {
-      try {
-         HikariConfig config = new HikariConfig();
-         config.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
-         config.setLeakDetectionThreshold(1000L);
-         config.validate();
-         Assert.assertEquals(2000L, config.getLeakDetectionThreshold());
-      }
-      catch (IllegalArgumentException ise) {
-         // pass
-      }
+      HikariConfig config = new HikariConfig();
+      config.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
+      config.setLeakDetectionThreshold(1000L);
+      config.validate();
+      Assert.assertEquals(0L, config.getLeakDetectionThreshold());
    }
 
    @Test