聊聊jedis连接池参数配置

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本文主要研究一下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(即检测所有空闲连接,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时使用,-1的话则使用takeFirst方法,否则使用pollFirst(borrowMaxWaitDuration)方法

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方法会构造EvictionConfig,minEvictableIdleDuration默认为30分钟;这里主要是针对负数进行了判断,负数则取的Long.MAX_VALUE;即softMinEvictableIdleDuration默认为-1,转换过来就是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方法在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方法会durationBetweenEvictionRuns(默认为-1)去startEvictor;当改值为负数时则执行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

参数类别 参数值 jedisConfig值 commons-pool默认值 解释
基本 lifo true true 后进先出
基本 fairness false false 非公平机制
数量 maxTotal 8 - 最大连接数
数量 maxIdle 8 - 最大空间连接数
数量 minIdle 0 - 最少空闲连接数
阻塞获取 blockWhenExhausted true true 连接池耗尽时,获取连接是否阻塞等待
阻塞获取 maxWaitMillis -1 -1 blockWhenExhausted为true时阻塞等待多久
健康检测 testOnCreate fasle fasle 创建连接的时候检测
健康检测 testOnBorrow false false 借用连接的时候检测
健康检测 testOnReturn false false 归还连接的时候检测
健康检测 testWhileIdle true false 在空闲连接检测时检测
evict durationBetweenEvictionRuns 30秒 -1 evictor线程运行间隔,-1为不运行
evict minEvictableIdleDuration 60秒 30分钟 连接空闲的最小时间
evict softMinEvictableIdleDuration -1 -1 -1即Long.MAX_VALUE,它与idleCount>minIdle条件一起考虑
evict numTestsPerEvictionRun -1 3 每次空闲连接回收器线程(如果有)运行时检查的连接数量, -1表示全部
evict evictionPolicyClassName DefaultEvictionPolicy DefaultEvictionPolicy 判断是否需要evict的PolicyClass
evict evictorShutdownTimeoutDuration 10s 10s 关闭evictor线程池的等待时间
jmx jmxEnabled true true 是否开启jmx
jmx jmxNamePrefix pool pool jmx名称前缀
jmx jmxNameBase null null null表示由pool自己定义jmxNameBase

JedisConfig默认帮我们配置了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(即检测所有空闲连接,默认值为3),利用evictor线程来检测空闲连接的健康情况

另外由聊聊jedis的return行为这篇分析可以得知在执行命令时若redis出问题,Jedis本身会标记底层connection为broken,在finally归还时会destory连接,保证连接池连接最终都会被清空重建。

另外在并发量比较大的场景,若要保证连接池的稳定数量则可以把minIdle设置成与maxTotal和maxIdle一样即可;若不想因为idle时间被频繁destory则可以设置minEvictableIdleTime为-1,evict方法始终返回false,evictor线程始终走的是testWhileIdle的逻辑;maxWaitMillis要设置一个合理值避免连接池耗尽阻塞线程,或者直接设置blockWhenExhausted为false

doc


聊聊jedis连接池参数配置
作者
codecraft
许可协议
CC BY 4.0
发布于
2023-09-24
修改于
2024-07-15
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