关于jedis:聊聊jedis连接池参数配置

序

本文次要钻研一下 jedis 连接池的参数配置

JedisConfig

redis/clients/jedis/JedisPoolConfig.java

public class JedisPoolConfig extends GenericObjectPoolConfig<Jedis> {public JedisPoolConfig() {// defaults to make your life with connection pool easier :)
    setTestWhileIdle(true);
    setMinEvictableIdleTimeMillis(60000);
    setTimeBetweenEvictionRunsMillis(30000);
    setNumTestsPerEvictionRun(-1);
  }
}

JedisPoolConfig 继承了 GenericObjectPoolConfig，同时默认配置了 testWhileIdle 为 true(默认为 false)，minEvictableIdleTime 为 60s(默认为 30 分钟 )，timeBetweenEvictionRuns 为 30s( 默认为 -1)，numTestsPerEvictionRun 为 -1(即检测所有闲暇连贯，默认值为 3 )

GenericObjectPoolConfig

org/apache/commons/pool2/impl/GenericObjectPoolConfig.java

public class GenericObjectPoolConfig<T> extends BaseObjectPoolConfig<T> {
    /**
     * The default value for the {@code maxTotal} configuration attribute.
     * @see GenericObjectPool#getMaxTotal()
     */
    public static final int DEFAULT_MAX_TOTAL = 8;

    /**
     * The default value for the {@code maxIdle} configuration attribute.
     * @see GenericObjectPool#getMaxIdle()
     */
    public static final int DEFAULT_MAX_IDLE = 8;

    /**
     * The default value for the {@code minIdle} configuration attribute.
     * @see GenericObjectPool#getMinIdle()
     */
    public static final int DEFAULT_MIN_IDLE = 0;


    private int maxTotal = DEFAULT_MAX_TOTAL;

    private int maxIdle = DEFAULT_MAX_IDLE;

    private int minIdle = DEFAULT_MIN_IDLE;
}

GenericObjectPoolConfig 继承了 BaseObjectPoolConfig，其 maxTotal 为 8，maxIdle 为 8，minIdle 为 0

BaseObjectPoolConfig

org/apache/commons/pool2/impl/BaseObjectPoolConfig.java

public abstract class BaseObjectPoolConfig<T> extends BaseObject implements Cloneable {
    private boolean lifo = DEFAULT_LIFO;
    public static final boolean DEFAULT_LIFO = true;

    private boolean fairness = DEFAULT_FAIRNESS;
    public static final boolean DEFAULT_FAIRNESS = false;

    private Duration maxWaitDuration = DEFAULT_MAX_WAIT;
    public static final Duration DEFAULT_MAX_WAIT = Duration.ofMillis(-1L);

    private Duration minEvictableIdleDuration = DEFAULT_MIN_EVICTABLE_IDLE_TIME;
    public static final Duration DEFAULT_MIN_EVICTABLE_IDLE_TIME =
            Duration.ofMillis(1000L * 60L * 30L);


    private Duration evictorShutdownTimeoutDuration = DEFAULT_EVICTOR_SHUTDOWN_TIMEOUT;
    public static final Duration DEFAULT_EVICTOR_SHUTDOWN_TIMEOUT =
            Duration.ofMillis(10L * 1000L);

    private Duration softMinEvictableIdleDuration = DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME;
    public static final Duration DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME =
            Duration.ofMillis(-1);

    private int numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
    public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;

    private EvictionPolicy<T> evictionPolicy; // Only 2.6.0 applications set this

    private String evictionPolicyClassName = DEFAULT_EVICTION_POLICY_CLASS_NAME;
    public static final String DEFAULT_EVICTION_POLICY_CLASS_NAME = DefaultEvictionPolicy.class.getName();

    private boolean testOnCreate = DEFAULT_TEST_ON_CREATE;
    public static final boolean DEFAULT_TEST_ON_CREATE = false;

    private boolean testOnBorrow = DEFAULT_TEST_ON_BORROW;
    public static final boolean DEFAULT_TEST_ON_BORROW = false;

    private boolean testOnReturn = DEFAULT_TEST_ON_RETURN;
    public static final boolean DEFAULT_TEST_ON_RETURN = false;

    private boolean testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
    public static final boolean DEFAULT_TEST_WHILE_IDLE = false;

    private Duration durationBetweenEvictionRuns = DEFAULT_TIME_BETWEEN_EVICTION_RUNS;
    public static final Duration DEFAULT_TIME_BETWEEN_EVICTION_RUNS = Duration
            .ofMillis(-1L);

    private boolean blockWhenExhausted = DEFAULT_BLOCK_WHEN_EXHAUSTED;
    public static final boolean DEFAULT_BLOCK_WHEN_EXHAUSTED = true;

    private boolean jmxEnabled = DEFAULT_JMX_ENABLE;
    public static final boolean DEFAULT_JMX_ENABLE = true;

    // TODO Consider changing this to a single property for 3.x
    private String jmxNamePrefix = DEFAULT_JMX_NAME_PREFIX;
    public static final String DEFAULT_JMX_NAME_PREFIX = "pool";

    private String jmxNameBase = DEFAULT_JMX_NAME_BASE;
    public static final String DEFAULT_JMX_NAME_BASE = null;
}

BaseObjectPoolConfig 定义了 lifo(默认为 true)、fairness(默认为 false)、maxWaitDuration(默认为 -1)、minEvictableIdleDuration(默认为 30 分钟 )、evictorShutdownTimeoutDuration( 默认为 10s)、softMinEvictableIdleDuration(默认为 -1)、numTestsPerEvictionRun(默认为 3 )、evictionPolicyClassName(默认为 DefaultEvictionPolicy.class.getName())、testOnCreate(默认为 false)、testOnBorrow(默认为 false)、testOnReturn(默认为 false)、testWhileIdle(默认为 false)、durationBetweenEvictionRuns(默认为 -1)、blockWhenExhausted(默认为 true)、jmxEnabled(默认为 true)、jmxNamePrefix(默认为 pool)、jmxNameBase(默认为 null)

maxWaitDuration

org/apache/commons/pool2/impl/GenericObjectPool.java

            if (blockWhenExhausted) {if (p == null) {if (borrowMaxWaitDuration.isNegative()) {p = idleObjects.takeFirst();
                    } else {p = idleObjects.pollFirst(borrowMaxWaitDuration);
                    }
                }
                if (p == null) {
                    throw new NoSuchElementException(appendStats("Timeout waiting for idle object, borrowMaxWaitDuration=" + borrowMaxWaitDuration));
                }
            }

borrow 的时候在 blockWhenExhausted 为 true 时应用，- 1 的话则应用 takeFirst 办法，否则应用 pollFirst(borrowMaxWaitDuration)办法

evict

getNumTests

org/apache/commons/pool2/impl/GenericObjectPool.java

    /**
     * Calculates the number of objects to test in a run of the idle object
     * evictor.
     *
     * @return The number of objects to test for validity
     */
    private int getNumTests() {final int numTestsPerEvictionRun = getNumTestsPerEvictionRun();
        if (numTestsPerEvictionRun >= 0) {return Math.min(numTestsPerEvictionRun, idleObjects.size());
        }
        return (int) (Math.ceil(idleObjects.size() /
                Math.abs((double) numTestsPerEvictionRun)));
    }

当 numTestsPerEvictionRun 为 - 1 时，返回的是 idleObjects.size()

EvictionConfig

org/apache/commons/pool2/impl/EvictionConfig.java

public class EvictionConfig {private static final Duration MAX_DURATION = Duration.ofMillis(Long.MAX_VALUE);
    private final Duration idleEvictDuration;
    private final Duration idleSoftEvictDuration;
    private final int minIdle;

    /**
     * Creates a new eviction configuration with the specified parameters.
     * Instances are immutable.
     *
     * @param idleEvictDuration Expected to be provided by
     *        {@link BaseGenericObjectPool#getMinEvictableIdleDuration()}
     * @param idleSoftEvictDuration Expected to be provided by
     *        {@link BaseGenericObjectPool#getSoftMinEvictableIdleDuration()}
     * @param minIdle Expected to be provided by
     *        {@link GenericObjectPool#getMinIdle()} or
     *        {@link GenericKeyedObjectPool#getMinIdlePerKey()}
     * @since 2.10.0
     */
    public EvictionConfig(final Duration idleEvictDuration, final Duration idleSoftEvictDuration, final int minIdle) {this.idleEvictDuration = PoolImplUtils.isPositive(idleEvictDuration) ? idleEvictDuration : MAX_DURATION;
        this.idleSoftEvictDuration = PoolImplUtils.isPositive(idleSoftEvictDuration) ? idleSoftEvictDuration : MAX_DURATION;
        this.minIdle = minIdle;
    }

    //......
}    

evict 办法会结构 EvictionConfig，minEvictableIdleDuration 默认为 30 分钟；这里次要是针对正数进行了判断，正数则取的 Long.MAX_VALUE；即 softMinEvictableIdleDuration 默认为 -1，转换过去就是 Long.MAX_VALUE

final EvictionConfig evictionConfig = new EvictionConfig(getMinEvictableIdleDuration(),
                        getSoftMinEvictableIdleDuration(),
                        getMinIdle());

DefaultEvictionPolicy

org/apache/commons/pool2/impl/DefaultEvictionPolicy.java

public class DefaultEvictionPolicy<T> implements EvictionPolicy<T> {

    @Override
    public boolean evict(final EvictionConfig config, final PooledObject<T> underTest, final int idleCount) {
        // @formatter:off
        return (config.getIdleSoftEvictDuration().compareTo(underTest.getIdleDuration()) < 0 &&
                config.getMinIdle() < idleCount) ||
                config.getIdleEvictDuration().compareTo(underTest.getIdleDuration()) < 0;
        // @formatter:on
    }
}

DefaultEvictionPolicy 的 evict 办法在 idleCount 大于 minIdle 且 idleDuration 大于 idleSoftEvictDuration(默认为 Long.MAX_VALUE)返回 true，或者 obj 的 idleDuration 大于 minEvictableIdleDuration(默认为 30 分钟 ) 返回 true

durationBetweenEvictionRuns

org/apache/commons/pool2/impl/BaseGenericObjectPool.java

    public final void setTimeBetweenEvictionRuns(final Duration timeBetweenEvictionRuns) {this.durationBetweenEvictionRuns = PoolImplUtils.nonNull(timeBetweenEvictionRuns, BaseObjectPoolConfig.DEFAULT_TIME_BETWEEN_EVICTION_RUNS);
        startEvictor(this.durationBetweenEvictionRuns);
    }

    final void startEvictor(final Duration delay) {synchronized (evictionLock) {final boolean isPositiverDelay = PoolImplUtils.isPositive(delay);
            if (evictor == null) { // Starting evictor for the first time or after a cancel
                if (isPositiverDelay) { // Starting new evictor
                    evictor = new Evictor();
                    EvictionTimer.schedule(evictor, delay, delay);
                }
            } else if (isPositiverDelay) { // Stop or restart of existing evictor: Restart
                synchronized (EvictionTimer.class) { // Ensure no cancel can happen between cancel / schedule calls
                    EvictionTimer.cancel(evictor, evictorShutdownTimeoutDuration, true);
                    evictor = null;
                    evictionIterator = null;
                    evictor = new Evictor();
                    EvictionTimer.schedule(evictor, delay, delay);
                }
            } else { // Stopping evictor
                EvictionTimer.cancel(evictor, evictorShutdownTimeoutDuration, false);
            }
        }
    }

setTimeBetweenEvictionRuns 办法会 durationBetweenEvictionRuns(默认为 -1)去 startEvictor；当改值为正数时则执行 EvictionTimer.cancel，即不启动 evictor 线程

cancel

org/apache/commons/pool2/impl/EvictionTimer.java

    /**
     * Removes the specified eviction task from the timer.
     *
     * @param evictor   Task to be cancelled.
     * @param timeout   If the associated executor is no longer required, how
     *                  long should this thread wait for the executor to
     *                  terminate?
     * @param restarting The state of the evictor.
     */
    static synchronized void cancel(final BaseGenericObjectPool<?>.Evictor evictor, final Duration timeout,
            final boolean restarting) {if (evictor != null) {evictor.cancel();
            remove(evictor);
        }
        if (!restarting && executor != null && taskMap.isEmpty()) {executor.shutdown();
            try {executor.awaitTermination(timeout.toMillis(), TimeUnit.MILLISECONDS);
            } catch (final InterruptedException e) {
                // Swallow
                // Significant API changes would be required to propagate this
            }
            executor.setCorePoolSize(0);
            executor = null;
        }
    }

evictorShutdownTimeoutDuration 即 executor.awaitTermination 的 timeout 参数

小结

JedisConfig 默认帮咱们配置了 testWhileIdle 为 true(默认为 false)，minEvictableIdleTime 为 60s(默认为 30 分钟 )，timeBetweenEvictionRuns 为 30s( 默认为 -1)，numTestsPerEvictionRun 为 -1(即检测所有闲暇连贯，默认值为 3 )，利用 evictor 线程来检测闲暇连贯的衰弱状况

另外由聊聊 jedis 的 return 行为这篇剖析能够得悉在执行命令时若 redis 出问题，Jedis 自身会标记底层 connection 为 broken，在 finally 偿还时会 destory 连贯，保障连接池连贯最终都会被清空重建。

另外在并发量比拟大的场景，若要保障连接池的稳固数量则能够把 minIdle 设置成与 maxTotal 和 maxIdle 一样即可；若不想因为 idle 工夫被频繁 destory 则能够设置 minEvictableIdleTime 为 -1，evict 办法始终返回 false，evictor 线程始终走的是 testWhileIdle 的逻辑；maxWaitMillis 要设置一个正当值防止连接池耗尽阻塞线程，或者间接设置 blockWhenExhausted 为 false

doc

• GenericObjectPool 参数解析
• JedisPool 资源池优化
• 一次拜访 Redis 延时高问题排查与总结
• 实战总结|一次拜访 Redis 延时高问题排查与总结（续）