HikariCP and maxLifetime

Question

I moved my project to HikariCP. Everything is going fine so far, but with one setting I'm having trouble.

It's the .setMaxLifetime(30*1000) setting in HikariConfig object. I get this warning

WARN com.zaxxer.hikari.HikariConfig - maxLifetime is less than 120000ms, using default 1800000ms.

I know that they recommend not setting is that low as I am trying to. But Unfortunately due to circumstances that I can not change, every TCP connection that is open longer than 50 secods will be terminated in our production environment.

Answer 1

i don't know your HikariCP Version, but in the version 2.2.4 you will find the reason why it will throw the above warning. HikariConfig.class (in the com.zaxxer.hikari.HikariConfig):

 private void More ...validateNumerics()
  {
     Logger logger = LoggerFactory.getLogger(getClass());

     if (connectionTimeout == Integer.MAX_VALUE) {
        logger.warn("No connection wait timeout is set, this might cause an infinite wait.");
     }

     if (minIdle < 0 || minIdle > maxPoolSize) {
        minIdle = maxPoolSize;
     }

     if (maxLifetime < 0) {
        logger.error("maxLifetime cannot be negative.");
        throw new IllegalArgumentException("maxLifetime cannot be negative.");
     }
     else if (maxLifetime > 0 && maxLifetime < TimeUnit.SECONDS.toMillis(120)) {
        logger.warn("maxLifetime is less than 120000ms, using default {}ms.", MAX_LIFETIME);
        maxLifetime = MAX_LIFETIME;
     }

     if (idleTimeout != 0 && idleTimeout < TimeUnit.SECONDS.toMillis(30)) {
        logger.warn("idleTimeout is less than 30000ms, using default {}ms.", IDLE_TIMEOUT);
        idleTimeout = IDLE_TIMEOUT;
     }
     else if (idleTimeout > maxLifetime && maxLifetime > 0) {
        logger.warn("idleTimeout is greater than maxLifetime, setting to maxLifetime.");
        idleTimeout = maxLifetime;
     }

from this code, the maxLifeTime is at least 120000ms, using default 1800000ms. so you can't set the maxLifeTime to 30000ms(30*1000). I guess your HikariCP version is at least older than 2.2.4.

But when you find the latest HikariCP version 2.7.4. it said "We strongly recommend setting this value, and it should be at least 30 seconds less than any database or infrastructure imposed connection time limit."

the same class HikariConfig.class:

private void validateNumerics() {
    if(this.maxLifetime != 0L && this.maxLifetime < TimeUnit.SECONDS.toMillis(30L)) {
        LOGGER.warn("{} - maxLifetime is less than 30000ms, setting to default {}ms.", this.poolName, Long.valueOf(MAX_LIFETIME));
        this.maxLifetime = MAX_LIFETIME;
    }

    if(this.idleTimeout + TimeUnit.SECONDS.toMillis(1L) > this.maxLifetime && this.maxLifetime > 0L) {
        LOGGER.warn("{} - idleTimeout is close to or more than maxLifetime, disabling it.", this.poolName);
        this.idleTimeout = 0L;
    }

    if(this.idleTimeout != 0L && this.idleTimeout < TimeUnit.SECONDS.toMillis(10L)) {
        LOGGER.warn("{} - idleTimeout is less than 10000ms, setting to default {}ms.", this.poolName, Long.valueOf(IDLE_TIMEOUT));
        this.idleTimeout = IDLE_TIMEOUT;
    }

    if(this.leakDetectionThreshold > 0L && !unitTest && (this.leakDetectionThreshold < TimeUnit.SECONDS.toMillis(2L) || this.leakDetectionThreshold > this.maxLifetime && this.maxLifetime > 0L)) {
        LOGGER.warn("{} - leakDetectionThreshold is less than 2000ms or more than maxLifetime, disabling it.", this.poolName);
        this.leakDetectionThreshold = 0L;
    }

    if(this.connectionTimeout < 250L) {
        LOGGER.warn("{} - connectionTimeout is less than 250ms, setting to {}ms.", this.poolName, Long.valueOf(CONNECTION_TIMEOUT));
        this.connectionTimeout = CONNECTION_TIMEOUT;
    }

    if(this.validationTimeout < 250L) {
        LOGGER.warn("{} - validationTimeout is less than 250ms, setting to {}ms.", this.poolName, Long.valueOf(VALIDATION_TIMEOUT));
        this.validationTimeout = VALIDATION_TIMEOUT;
    }

    if(this.maxPoolSize < 1) {
        this.maxPoolSize = this.minIdle <= 0?10:this.minIdle;
    }

    if(this.minIdle < 0 || this.minIdle > this.maxPoolSize) {
        this.minIdle = this.maxPoolSize;
    }

}

from this code, the maxLifeTime has been updated to 30000ms at least in this version.

So now please update your HikariCP version to the latest version 2.7.4 if you want to set maxLifeTime to 30000ms.

But if you update your HikariCP version to 2.7.4 with JDK 8, i also recommend you two points:

1. to set maxLifeTime value to be at least 30000ms.

2. to set maxLifeTime value few minute less than mysql's wait_timeout(show variables like "%timeout%") to avoid broken connection exception.