brettwooldridge/HikariCP · error · IllegalStateException

${poolName} - is not suspendable

Error message

${poolName} - is not suspendable

What it means

suspendPool() throws IllegalStateException when the pool was created without allowPoolSuspension=true, because such pools use SuspendResumeLock.FAUX_LOCK (a no-op) and cannot actually suspend. Suspension replaces a semaphore, so it must be enabled at config time.

Source

Thrown at src/main/java/com/zaxxer/hikari/pool/HikariPool.java:391

   @Override
   public int getThreadsAwaitingConnection()
   {
      return connectionBag.getWaitingThreadCount();
   }

   /** {@inheritDoc} */
   @Override
   public void softEvictConnections()
   {
      connectionBag.values().forEach(poolEntry -> softEvictConnection(poolEntry, "(connection evicted)", false /* not owner */));
   }

   /** {@inheritDoc} */
   @Override
   public synchronized void suspendPool()
   {
      if (suspendResumeLock == SuspendResumeLock.FAUX_LOCK) {
         throw new IllegalStateException(poolName + " - is not suspendable");
      }
      else if (poolState != POOL_SUSPENDED) {
         suspendResumeLock.suspend();
         poolState = POOL_SUSPENDED;
      }
   }

   /** {@inheritDoc} */
   @Override
   public synchronized void resumePool()
   {
      if (poolState == POOL_SUSPENDED) {
         poolState = POOL_NORMAL;
         fillPool(false);
         suspendResumeLock.resume();
      }
   }

View on GitHub (pinned to a4d93f4f85)

Solutions

1. Set allowPoolSuspension=true in the pool config before creating the DataSource
2. Remember suspension requires care: after suspend, you should usually resume promptly and connections queued via acquire will block (consider com.zaxxer.hikari.throwIfSuspended)
3. If you did not intend to suspend, fix the calling code (monitoring/JMX client) that invokes suspendPool
4. Verify via HikariConfigMXBean.isAllowPoolSuspension() before calling suspend

Example fix

// before
HikariConfig cfg = new HikariConfig();
// allowPoolSuspension defaults to false
hikariPoolMXBean.suspendPool(); // IllegalStateException

// after
cfg.setAllowPoolSuspension(true);
HikariDataSource ds = new HikariDataSource(cfg);
hikariPoolMXBean.suspendPool(); // works; remember to resumePool() after

HikariConfig cfg = new HikariConfig();
cfg.setAllowPoolSuspension(true); // required before suspendPool() can work

try { mxBean.suspendPool(); }
catch (IllegalStateException e) {
    if (e.getMessage().contains("is not suspendable")) { /* enable flag and recreate pool */ }
}

When it happens

Trigger: Calling HikariPool.suspendPool() (via JMX MBean hikariConfigMXBean or programmatically) when allowPoolSuspension was left at default false; Dropwizard/ops tooling trying to pause a pool for DB maintenance.

Common situations: Using HikariCP MBeans to suspend during failover/maintenance while forgetting the config flag; rolling restart tooling that assumes suspension is available.

Related errors

• poolName cannot contain ':' when used with JMX
• connectionTimeout cannot be less than ${SOFT_TIMEOUT_FLOOR}m
• idleTimeout cannot be negative
• maxPoolSize cannot be less than 1
• minimumIdle cannot be negative

AI-assisted analysis of brettwooldridge/HikariCP@a4d93f4f85 (2026-08-14). Data as JSON: /api/errors/99526ace91d0f8f9. Report an issue: GitHub.