Hbase1.3 生产优化，源码分析

hbase.regionserver.handler.count：默认为30，服务器端用来处理用户请求的线程数。生产线上通常需要将该值调到100～200。线上：128
hbase.ipc.server.callqueue.handler.factor : 默认为0，服务器端设置队列个数，假如该值为0.1，那么服务器就会设置handler.count * 0.1 = 30 * 0.1 = 3个队列。线上：0.2
hbase.ipc.server.callqueue.read.ratio : 默认为0，服务器端设置读写业务分别占用的队列百分比以及handler百分比。假如该值为0.5，表示读写各占一半队列，同时各占一半handler。线上：0.6
hbase.ipc.server.call.queue.scan.ratio：默认为0，服务器端为了将get和scan隔离设置了该参数。线上：0.1

if (callqReadShare > 0) {
      // at least 1 read handler and 1 write handler
      callExecutor = new RWQueueRpcExecutor("default.RWQ", Math.max(2, handlerCount),
        maxQueueLength, priority, conf, server);
    }

public RWQueueRpcExecutor(final String name, final int handlerCount, final int maxQueueLength,
      final PriorityFunction priority, final Configuration conf, final Abortable abortable) {
    super(name, handlerCount, maxQueueLength, priority, conf, abortable);
    //默认为0，服务器端设置读写业务分别占用的队列百分比以及handler百分比。
    //假如该值为0.5，表示读写各占一半队列，同时各占一半handler
    float callqReadShare = getReadShare(conf);
    // hbase.ipc.server.callqueue.scan.ratio=0.2
    float callqScanShare = getScanShare(conf);
    //写队列 10*0.5=5对列数
    numWriteQueues = calcNumWriters(this.numCallQueues, callqReadShare);
    //线程数 100*0.5=50
    writeHandlersCount = Math.max(numWriteQueues, calcNumWriters(handlerCount, callqReadShare));

    //numCallQueues减去写队列数 10-5=5
    int readQueues = calcNumReaders(this.numCallQueues, callqReadShare);
    //线程数 50
    int readHandlers = Math.max(readQueues, calcNumReaders(handlerCount, callqReadShare));

    //scanQueues = 5*0.2=1
    int scanQueues = Math.max(0, (int)Math.floor(readQueues * callqScanShare));
    //scanQueues = 50*0.2=10
    int scanHandlers = Math.max(0, (int)Math.floor(readHandlers * callqScanShare));

    if ((readQueues - scanQueues) > 0) {
      //readQueues=5-1=4 因为scan也属于读的一部分，所以scan要从read中扣取一部分资源
      readQueues -= scanQueues;
      //readQueues=50-10=40
      readHandlers -= scanHandlers;
    } else {
      scanQueues = 0;
      scanHandlers = 0;
    }

    numReadQueues = readQueues;
    readHandlersCount = readHandlers;
    numScanQueues = scanQueues;
    scanHandlersCount = scanHandlers;
    //队列分负载均衡，策咯是随机打入一个相关队列
    this.writeBalancer = getBalancer(numWriteQueues);
    this.readBalancer = getBalancer(numReadQueues);
    this.scanBalancer = numScanQueues > 0 ? getBalancer(numScanQueues) : null;

    initializeQueues(numWriteQueues);
    initializeQueues(numReadQueues);
    initializeQueues(numScanQueues);