【memcached】自动维护线程

在SockIOPool中，有一个类：MaintThread

 

是Pool的自我维护的线程类。

 

这个类的使用，看代码是要自己创建一个实例，输入SockIOPool对象进去进行运转；

 

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在最新的2.6.1版本中，没有看到有维护线程的启动，在2.0版本，在初始化的时候，维护线程就启动了：

	/** 
	 * Initializes the pool. 
	 */
	public void initialize() {

		synchronized( this ) {

			// check to see if already initialized
			if ( initialized
					&& ( buckets != null || consistentBuckets != null )
					&& ( availPool != null )
					&& ( busyPool != null ) ) {
				log.error( "++++ trying to initialize an already initialized pool" );
				return;
			}

			// pools
			availPool   = new HashMap<String,Map<SockIO,Long>>( servers.length * initConn );
			busyPool    = new HashMap<String,Map<SockIO,Long>>( servers.length * initConn );
			deadPool    = new IdentityHashMap<SockIO,Integer>();

			hostDeadDur = new HashMap<String,Long>();
			hostDead    = new HashMap<String,Date>();
			createShift = new HashMap<String,Integer>();
			maxCreate   = (poolMultiplier > minConn) ? minConn : minConn / poolMultiplier;		// only create up to maxCreate connections at once

			log.debug( "++++ initializing pool with following settings:" );
			log.debug( "++++ initial size: " + initConn );
			log.debug( "++++ min spare   : " + minConn );
			log.debug( "++++ max spare   : " + maxConn );

			// if servers is not set, or it empty, then
			// throw a runtime exception
			if ( servers == null || servers.length <= 0 ) {
				log.error( "++++ trying to initialize with no servers" );
				throw new IllegalStateException( "++++ trying to initialize with no servers" );
			}

			// initalize our internal hashing structures
			if ( this.hashingAlg == CONSISTENT_HASH )
				populateConsistentBuckets();
			else
				populateBuckets();

			// mark pool as initialized
			this.initialized = true;

			// start maint thread
			if ( this.maintSleep > 0 )
				this.startMaintThread();
		}
	}

 

在最后，如果设置的维护时间大于0，就会启动维护线程