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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
