Minor code cleanups.

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

@@ -619,7 +619,7 @@ private boolean softEvictConnection(final PoolEntry poolEntry, final String reas
    private ScheduledExecutorService initializeHouseKeepingExecutorService()
    {
       if (config.getScheduledExecutor() == null) {
-         final var threadFactory = Optional.ofNullable(config.getThreadFactory()).orElseGet(() -> new DefaultThreadFactory(poolName + " housekeeper", true));
+         final var threadFactory = Optional.ofNullable(config.getThreadFactory()).orElseGet(() -> new DefaultThreadFactory(poolName + " housekeeper"));
          final var executor = new ScheduledThreadPoolExecutor(1, threadFactory, new ThreadPoolExecutor.DiscardPolicy());
          executor.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
          executor.setRemoveOnCancelPolicy(true);
@@ -665,9 +665,9 @@ protected void update() {
     * timeout occurred when trying to acquire a Connection from the pool.  If there was an underlying cause for the
     * timeout, e.g. a SQLException thrown by the driver while trying to create a new Connection, then use the
     * SQL State from that exception as our own and additionally set that exception as the "next" SQLException inside
-    * of our exception.
+    * our exception.
     *
-    * As a side-effect, log the timeout failure at DEBUG, and record the timeout failure in the metrics tracker.
+    * As a side effect, log the timeout failure at DEBUG, and record the timeout failure in the metrics tracker.
     *
     * @param startTime the start time (timestamp) of the acquisition attempt
     * @return a SQLException to be thrown from {@link #getConnection()}
@@ -758,7 +758,7 @@ private synchronized boolean shouldContinueCreating() {
    }
 
    /**
-    * The house keeping task to retire and maintain minimum idle connections.
+    * The housekeeping task to retire and maintain minimum idle connections.
     */
    private final class HouseKeeper implements Runnable
    {
@@ -797,22 +797,20 @@ else if (now > plusMillis(previous, (3 * housekeepingPeriodMs) / 2)) {
 
             previous = now;
 
-            var afterPrefix = "Pool ";
             if (idleTimeout > 0L && config.getMinimumIdle() < config.getMaximumPoolSize()) {
                logPoolState("Before cleanup ");
-               afterPrefix = "After cleanup  ";
-
                final var notInUse = connectionBag.values(STATE_NOT_IN_USE);
-               var toRemove = notInUse.size() - config.getMinimumIdle();
+               var maxToRemove = notInUse.size() - config.getMinimumIdle();
                for (PoolEntry entry : notInUse) {
-                  if (toRemove > 0 && elapsedMillis(entry.lastAccessed, now) > idleTimeout && connectionBag.reserve(entry)) {
+                  if (maxToRemove > 0 && elapsedMillis(entry.lastAccessed, now) > idleTimeout && connectionBag.reserve(entry)) {
                      closeConnection(entry, "(connection has passed idleTimeout)");
-                     toRemove--;
+                     maxToRemove--;
                   }
                }
+               logPoolState("After cleanup  ");
             }
-
-            logPoolState(afterPrefix);
+            else
+               logPoolState("Pool ");
 
             fillPool(true); // Try to maintain minimum connections
          }
@@ -822,13 +820,6 @@ else if (now > plusMillis(previous, (3 * housekeepingPeriodMs) / 2)) {
       }
    }
 
-   private static class CustomDiscardPolicy implements RejectedExecutionHandler
-   {
-      @Override
-      public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
-      }
-   }
-
    private final class MaxLifetimeTask implements Runnable
    {
       private final PoolEntry poolEntry;

src/main/java/com/zaxxer/hikari/pool/PoolBase.java

@@ -600,7 +600,7 @@ private void createNetworkTimeoutExecutor(final DataSource dataSource, final Str
       }
       else {
          ThreadFactory threadFactory = config.getThreadFactory();
-         threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory(poolName + " network timeout executor", true);
+         threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory(poolName + " network timeout executor");
          ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newCachedThreadPool(threadFactory);
          executor.setKeepAliveTime(15, SECONDS);
          executor.allowCoreThreadTimeOut(true);

src/main/java/com/zaxxer/hikari/util/UtilityElf.java

@@ -118,14 +118,7 @@ public static <T> T createInstance(final String className, final Class<T> clazz,
     */
    public static ThreadPoolExecutor createThreadPoolExecutor(final int queueSize, final String threadName, ThreadFactory threadFactory, final RejectedExecutionHandler policy)
    {
-      if (threadFactory == null) {
-         threadFactory = new DefaultThreadFactory(threadName, true);
-      }
-
-      var queue = new LinkedBlockingQueue<Runnable>(queueSize);
-      var executor = new ThreadPoolExecutor(1 /*core*/, 1 /*max*/, 5 /*keepalive*/, SECONDS, queue, threadFactory, policy);
-      executor.allowCoreThreadTimeOut(true);
-      return executor;
+      return createThreadPoolExecutor(new LinkedBlockingQueue<>(queueSize), threadName, threadFactory, policy);
    }
 
    /**
@@ -140,7 +133,7 @@ public static ThreadPoolExecutor createThreadPoolExecutor(final int queueSize, f
    public static ThreadPoolExecutor createThreadPoolExecutor(final BlockingQueue<Runnable> queue, final String threadName, ThreadFactory threadFactory, final RejectedExecutionHandler policy)
    {
       if (threadFactory == null) {
-         threadFactory = new DefaultThreadFactory(threadName, true);
+         threadFactory = new DefaultThreadFactory(threadName);
       }
 
       var executor = new ThreadPoolExecutor(1 /*core*/, 1 /*max*/, 5 /*keepalive*/, SECONDS, queue, threadFactory, policy);
@@ -186,14 +179,21 @@ public static int getTransactionIsolation(final String transactionIsolationName)
       return -1;
    }
 
-   public static final class DefaultThreadFactory implements ThreadFactory {
+   public static class CustomDiscardPolicy implements RejectedExecutionHandler
+   {
+      @Override
+      public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
+      }
+   }
 
+   public static final class DefaultThreadFactory implements ThreadFactory
+   {
       private final String threadName;
       private final boolean daemon;
 
-      public DefaultThreadFactory(String threadName, boolean daemon) {
+      public DefaultThreadFactory(String threadName) {
          this.threadName = threadName;
-         this.daemon = daemon;
+         this.daemon = true;
       }
 
       @Override

src/test/java/com/zaxxer/hikari/pool/HouseKeeperCleanupTest.java

@@ -43,7 +43,7 @@ public class HouseKeeperCleanupTest
    @Before
    public void before() throws Exception
    {
-      ThreadFactory threadFactory = new UtilityElf.DefaultThreadFactory("global housekeeper", true);
+      ThreadFactory threadFactory = new UtilityElf.DefaultThreadFactory("global housekeeper");
 
       executor = new ScheduledThreadPoolExecutor(1, threadFactory, new ThreadPoolExecutor.DiscardPolicy());
       executor.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);