Memcached的使用
Memcached的使用
一 、 安装Memcached及Memcached配置和状态查询 （此处将其作为系统服务安装）
????? 要想使用Memcached做缓存首先需要安装Memcached服务，安装方法如下：
????? 1. 下载Memcached：http://code.jellycan.com/memcached/ 现在的最新版本是1.2.6.注意下载正确的版本，windows 服务的话下载win32 binary。
????? 2.解压之后放在硬盘的目录下，如：D:\memcached. 然后在运行中输入cmd进入命令行，进入到Memcached.exe 所在的目录，例如：D:\memcached,然后输入：Memcached –d install,即可完成安装。
????????? Memcached还有其他的一些常用的命令如下：
????? -p 监听的端口
????? -l 连接的IP地址, 默认是本机
????? -d start 启动memcached服务
????? -d restart 重起memcached服务
????? -d stop|shutdown 关闭正在运行的memcached服务
????? -d install 安装memcached服务
????? -d uninstall 卸载memcached服务
????? -u 以的身份运行 (仅在以root运行的时候有效)
????? -m 最大内存使用，单位MB。默认64MB
????? -M 内存耗尽时返回错误，而不是删除项
????? -c 最大同时连接数，默认是1024
????? -f 块大小增长因子，默认是1.25
????? -n 最小分配空间，key+value+flags默认是48
????? -h 显示帮助
????????? 按照上面的安装步骤安装之后，使用memcached –m 200来调整最大内存占用之后会发现没有起作用，总是默认的64MB的内存，在网上搜了一下，原因是注册表中并没有写入信息，可以这样来修改。
???????? 1. memcached –d shutdown 首先关闭memcached服务。
????????2.进入注册表，找到HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\memcachedServer， 在其中有一个ImagePath项，值为"d:\memcached\memcached.exe" -drunservice，在后面加上-l 127.0.0.1 -m 3000 -c 2048。
??????? 3.memcached –d start 启动memcached服务，这样就将memcached的最大内存修改为了3000MB。
??????? 对Memcached缓存服务的状态查询，可以先telnet连接上服务：telnet 127.0.0.1 11211 ，然后使用 stats命令查看缓存服务的状态，会返回如下的数据：???
??????? time:??? 1255537291?????????????????????????????? 服务器当前的unix时间戳
??????? total_items:??? 54???????????????????????????????????? 从服务器启动以后存储的items总数量
??????? connection_structures:??? 19??????????????????? 服务器分配的连接构造数
??????? version:??? 1.2.6??????????????????????????????????????? memcache版本
??????? limit_maxbytes:??? 67108864??????????????????? 分配给memcache的内存大小（字节）
??????? cmd_get:??? 1645????????????????????????????????????? get命令（获取）总请求次数
??????? evictions:??? 0??????????????????????????????????????????? 为获取空闲内存而删除的items数（分配给memcache的空间用满后需
???????????????????????????????????????????????????????????????????????? 要删除旧的items来得到空间分配给新的items）
??????? total_connections:??? 19?????????????????????????? 从服务器启动以后曾经打开过的连接数
??????? bytes:??? 248723????????????????????????????????????? 当前服务器存储items占用的字节数
??????? threads:??? 1???????????????????????????????????????????? 当前线程数
??????? get_misses:??? 82????????????????????????????????????? 总未命中次数
??????? pointer_size:??? 32??????????????????????????????????? 当前操作系统的指针大小（32位系统一般是32bit）
??????? bytes_read:??? 490982????????????????????????????? 总读取字节数（请求字节数）
??????? uptime:??? 161?????????????????????????????????????????? 服务器已经运行的秒数
??????? curr_connections:??? 18???????????????????????????? 当前打开着的连接数
??????? pid:??? 2816?????????????????????????????????????????????? memcache服务器的进程ID
??????? bytes_written:??? 16517259???????????????????? 总发送字节数（结果字节数）
??????? get_hits:??? 1563????????????????????????????????????? 总命中次数
??????? cmd_set:??? 54????????????????????????????????????????? set命令（保存）总请求次数
??????? curr_items:??? 28?????????????????????????????????????? 服务器当前存储的items数量
二、客户端使用
????? 下载memcached javaclient：[url]https://github.com/gwhalin/Memcached-Java-Client [/url]?? 1解压后将java_memcached-release_2.5.3.jar jar包添加到工程的classpath中
??? 2 利用memcached java client 一个简单的应用
?
/**
?* Copyright (c) 2008 Greg Whalin
?* All rights reserved.
?*
?* This library is free software; you can redistribute it and/or
?* modify it under the terms of the BSD license
?*
?* This library is distributed in the hope that it will be
?* useful, but WITHOUT ANY WARRANTY; without even the implied
?* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
?* PURPOSE.
?*
?* You should have received a copy of the BSD License along with this
?* library.
?*
?* @author Greg Whalin <greg@meetup.com>
?*/
package com.danga.MemCached.test;
import java.util.Hashtable;
import com.danga.MemCached.MemCachedClient;
import com.danga.MemCached.SockIOPool;
public class MemcachedTest {
??? // store results from threads
??? private static Hashtable<Integer,StringBuilder> threadInfo =
??? ??? new Hashtable<Integer,StringBuilder>();
???
??? /**
??? ?* This runs through some simple tests of the MemcacheClient.
??? ?*
??? ?* Command line args:
??? ?* args[0] = number of threads to spawn生产的线程的数目
??? ?* args[1] = number of runs per thread 每个线程操作次数
??? ?* args[2] = size of object to store
??? ?*
??? ?* @param args the command line arguments
??? ?*/
??? public static void main(String[] args) {
??? ??? //String[] serverlist = { "hengtiandesk144:11211", "hengtiandesk144:11212" };
??? ??? String[] serverlist = { "localhost:11211" };
??? ??? // initialize the pool for memcache servers
??? ??? SockIOPool pool = SockIOPool.getInstance();
??? ??? pool.setServers( serverlist );
??? ??? pool.setInitConn(5);
??? ??? pool.setMinConn(5);
??? ???
??? ??? pool.setMaxConn(50);
??? ??? //Set the sleep time between runs of the pool maintenance thread.
??? ??? pool.setMaintSleep(30);
??? ??? //Sets the Nagle alg flag for the pool.
??? ??? pool.setNagle(false);
??? ??? pool.initialize();
??? ??? /*int threads = Integer.parseInt(args[0]);
??? ??? int runs = Integer.parseInt(args[1]);
??? ??? int size = 1024 * Integer.parseInt(args[2]);??? // how many kilobytes
??? ??? */
??? ??? int threads = Integer.parseInt("20");
??? ??? int runs = Integer.parseInt("30");
??? ??? int size = 1024 * Integer.parseInt("10");??? // how many kilobytes
??? ??? // get object to store
??? ??? int[] obj = new int[size];
??? ??? for (int i = 0; i < size; i++) {
??? ??? ??? obj[i] = i;
??? ??? }
??? ??? String[] keys = new String[size];
??? ??? for (int i = 0; i < size; i++) {
??? ??? ??? keys[i] = "test_key" + i;
??? ??? }
??? ??? for (int i = 0; i < threads; i++) {? //模仿连接服务器数目
??? ??? ??? bench b = new bench(runs, i, obj, keys);
??? ??? ??? b.start();
??? ??? }
??? ??? int i = 0;
??? ??? while (i < threads) {
??? ??? ??? if (threadInfo.containsKey(new Integer(i))) {
??? ??? ??? ??? System.out.println(threadInfo.get( new Integer( i ) ) );
??? ??? ??? ??? i++;
??? ??? ??? }
??? ??? ??? else {
??? ??? ??? ??? try {
??? ??? ??? ??? ??? Thread.sleep(1000);
??? ??? ??? ??? }
??? ??? ??? ??? catch (InterruptedException e) {
??? ??? ??? ??? ??? e.printStackTrace();
??? ??? ??? ??? }
??? ??? ??? }
??? ??? }
??? ??? pool.shutDown();
??? ??? System.exit(1);
??? }
??? /**
??? ?* Test code per thread.
??? ?*/
??? private static class bench extends Thread {
??? ??? private int runs;
??? ??? private int threadNum;
??? ??? private int[] object;
??? ??? private String[] keys;
??? ??? private int size;
??? ??? public bench(int runs, int threadNum, int[] object, String[] keys) {
??? ??? ??? this.runs = runs;
??? ??? ??? this.threadNum = threadNum;
??? ??? ??? this.object = object;
??? ??? ??? this.keys = keys;
??? ??? ??? this.size = object.length;
??? ??? }
??? ??? @SuppressWarnings("deprecation")
??? ??? public void run() {
??????????? //单线程，多线程不安全
??? ??? ??? StringBuilder result = new StringBuilder();
??? ??? ??? // get client instance
??? ??? ??? MemCachedClient mc = new MemCachedClient();
??? ??? ??? mc.setCompressEnable(false);
??? ??? ??? mc.setCompressThreshold(0);
??? ??? ??? // time deletes
??? ??? ??? long start = System.currentTimeMillis();
??? ??? ??? for (int i = 0; i < runs; i++) {
??? ??? ??? ??? mc.delete(keys[i]);
??? ??? ??? }
??? ??? ??? long elapse = System.currentTimeMillis() - start;
??? ??? ??? float avg = (float) elapse / runs;
??? ??? ??? result.append("\nthread " + threadNum + ": runs: " + runs + " deletes of obj " + (size/1024) + "KB -- avg time per req " + avg + " ms (total: " + elapse + " ms)");
??? ??? ??? // time stores
??? ??? ??? start = System.currentTimeMillis();
??? ??? ??? for (int i = 0; i < runs; i++) {
??? ??? ??? ??? //System.out.println(keys[i]+object[i]);
??? ??? ??? ??? mc.set(keys[i], object[i]);
??? ??? ??? }
??? ??? ??? elapse = System.currentTimeMillis() - start;
??? ??? ??? avg = (float) elapse / runs;
??? ??? ??? result.append("\nthread " + threadNum + ": runs: " + runs + " stores of obj " + (size/1024) + "KB -- avg time per req " + avg + " ms (total: " + elapse + " ms)");
???????????
??? ??? ??? //?? time gets
??? ??? ??? start = System.currentTimeMillis();
??? ??? ??? for (int i = 0; i < runs; i++) {
??? ??? ??? ??? mc.get(keys[i]);
??? ??? ??? }
??? ??? ??? elapse = System.currentTimeMillis() - start;
??? ??? ??? avg = (float) elapse / runs;
??? ??? ??? result.append("\nthread " + threadNum + ": runs: " + runs + " gets of obj " + (size/1024) + "KB -- avg time per req " + avg + " ms (total: " + elapse + " ms)");
??? ??? ??? threadInfo.put(new Integer(threadNum), result);
??? ??? }
??? }
}
?
?
java_memcached-release_2.5.3.jar memcached-1.2.6-win32-bin.zip java_memcached-release_2.5.2.zip memcached-1.2.6-win32-src.zip java_memcached-release_2.5.2.jar