Configurable MaxLifeTime Variance

src/main/java/com/zaxxer/hikari/HikariConfig.java

@@ -53,6 +53,7 @@ public class HikariConfig implements HikariConfigMXBean
    private static final long SOFT_TIMEOUT_FLOOR = Long.getLong("com.zaxxer.hikari.timeoutMs.floor", 250L);
    private static final long IDLE_TIMEOUT = MINUTES.toMillis(10);
    private static final long MAX_LIFETIME = MINUTES.toMillis(30);
+   private static final double DEFAULT_MAX_LIFETIME_VARIANCE = 2.5;
    private static final long DEFAULT_KEEPALIVE_TIME = 0L;
    private static final int DEFAULT_POOL_SIZE = 10;
 
@@ -66,6 +67,7 @@ public class HikariConfig implements HikariConfigMXBean
    private volatile long idleTimeout;
    private volatile long leakDetectionThreshold;
    private volatile long maxLifetime;
+   private volatile double maxLifetimeVariance;
    private volatile int maxPoolSize;
    private volatile int minIdle;
    private volatile String username;
@@ -119,6 +121,7 @@ public HikariConfig()
       minIdle = -1;
       maxPoolSize = -1;
       maxLifetime = MAX_LIFETIME;
+      maxLifetimeVariance = DEFAULT_MAX_LIFETIME_VARIANCE;
       connectionTimeout = CONNECTION_TIMEOUT;
       validationTimeout = VALIDATION_TIMEOUT;
       idleTimeout = IDLE_TIMEOUT;
@@ -229,6 +232,17 @@ public void setLeakDetectionThreshold(long leakDetectionThresholdMs)
       this.leakDetectionThreshold = leakDetectionThresholdMs;
    }
 
+   /** {@inheritDoc} */
+   @Override
+   public double getMaxLifetimeVariance()
+   {
+      return maxLifetimeVariance;
+   }
+
+   /** {@inheritDoc} */
+   @Override
+   public void setMaxLifetimeVariance(double maxLifetimeVariance) { this.maxLifetimeVariance = maxLifetimeVariance; }
+
    /** {@inheritDoc} */
    @Override
    public long getMaxLifetime()

src/main/java/com/zaxxer/hikari/HikariConfigMXBean.java

@@ -93,6 +93,24 @@ public interface HikariConfigMXBean
     */
    void setLeakDetectionThreshold(long leakDetectionThresholdMs);
 
+   /**
+    * This property controls the percentage of a connections maximum lifetime that will be used as variance/jitter.
+    * This percentage will be a maximum and random variances up to this percentage will be subtracted from the defined
+    * maxLifeTime value.
+    *
+    * @return the maximum percentage of a connections maxLifeTime to be utilized as a variance
+    */
+   double getMaxLifetimeVariance();
+
+   /**
+    * This property controls the percentage of a connections maximum lifetime that will be used as variance/jitter.
+    * This percentage will be a maximum and random variances up to this percentage will be subtracted from the defined
+    * maxLifeTime value.
+    *
+    * @param maxLifetimeVariance the maximum percentage of maxLifeTime that should be used for variance
+    */
+   void setMaxLifetimeVariance(double maxLifetimeVariance);
+
    /**
     * This property controls the maximum lifetime of a connection in the pool. When a connection reaches this
     * timeout, even if recently used, it will be retired from the pool. An in-use connection will never be

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

@@ -452,7 +452,7 @@ int[] getPoolStateCounts()
    // ***********************************************************************
 
    /**
-    * Creating new poolEntry.  If maxLifetime is configured, create a future End-of-life task with 2.5% variance from
+    * Creating new poolEntry.  If maxLifetime is configured, create a future End-of-life task with configurable variance from
     * the maxLifetime time to ensure there is no massive die-off of Connections in the pool.
     */
    private PoolEntry createPoolEntry()
@@ -462,8 +462,7 @@ private PoolEntry createPoolEntry()
 
          final var maxLifetime = config.getMaxLifetime();
          if (maxLifetime > 0) {
-            // variance up to 2.5% of the maxlifetime
-            final var variance = maxLifetime > 10_000 ? ThreadLocalRandom.current().nextLong( maxLifetime / 40 ) : 0;
+            final var variance = maxLifetime > 10_000 ? ThreadLocalRandom.current().nextLong( Math.round(maxLifetime * (config.getMaxLifetimeVariance() / 100)) ) : 0;
             final var lifetime = maxLifetime - variance;
             poolEntry.setFutureEol(houseKeepingExecutorService.schedule(new MaxLifetimeTask(poolEntry), lifetime, MILLISECONDS));
          }

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

@@ -138,6 +138,9 @@ else if (paramClass == long.class) {
          else if (paramClass == short.class) {
             writeMethod.invoke(target, Short.parseShort(propValue.toString()));
          }
+         else if (paramClass == double.class) {
+            writeMethod.invoke(target, Double.parseDouble(propValue.toString()));
+         }
          else if (paramClass == boolean.class || paramClass == Boolean.class) {
             writeMethod.invoke(target, Boolean.parseBoolean(propValue.toString()));
          }