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用Jetty和redis实现接入服务器adapter
传统的服务器端为若干个客户端提供服务,一般需要开启多个服务器端进程。为了进一步提升服务器端的处理能力,可以如下图所示将服务解耦为两部分(adapter与workers),它们之间通过消息队列传输数据,其中workers处理具体业务,adapter负责接入请求以及反馈结果,具体包含下面两个工作。
1,将所有客户端的请求发送到消息队列(进而传给后台处理)
2,后台处理完毕后将结果返回响应队列,client adapter获取到结果后返回给相应客户端。
流程图如下:
我们选择用Jetty(8),redis以及php简单实现这个场景,主要用到Jetty的continuation机制和redis的list先进先出数据结构
接入服务器:
A.1,先配置一个服务器如下,同时开启一个守护线程阻塞监听response queue(用到json lib库以及jedis库)
package test;import java.util.HashMap;import java.util.List;import org.eclipse.jetty.continuation.Continuation;import org.eclipse.jetty.server.*;import org.eclipse.jetty.server.nio.SelectChannelConnector;import org.eclipse.jetty.servlet.ServletContextHandler;import org.eclipse.jetty.servlet.ServletHolder;import org.eclipse.jetty.util.thread.QueuedThreadPool;import org.json.simple.*;import redis.clients.jedis.Jedis;public class PJetty{ public static HashMap<String,Continuation>globalMap = new HashMap<String,Continuation>(); // 用一个守护线程阻塞等待结果队列返回数据 public static class DaemonThread extends Thread{ private JSONObject obj = new JSONObject(); private Jedis jedis = new Jedis("127.0.0.1",6379); private List<String> res; public void run(){ while(true){ // 阻塞等待响应队列 res = jedis.brpop(0, "response_queue"); // 获取结果信息 String response = res.get(1); obj=(JSONObject) JSONValue.parse(response); String request_sid = obj.get("request_sid").toString(); String result = obj.get("results").toString(); if(request_sid == null){ continue; } // 通过消息中的连接的sessonid获取到响应的continuation实例,然后设置结果信息再唤醒实例 Continuation con = globalMap.get(request_sid); if(con == null){continue;} globalMap.remove(request_sid); //客户端异常断开这里会抛错 try{ con.setAttribute("results", result); con.resume(); } catch(Exception e){ continue; } } } } public static void main(String[] args) throws Exception { //开启守护线程去阻塞等待响应结果队列,唤醒请求 DaemonThread dt = new DaemonThread(); dt.start(); //设置connectors SelectChannelConnector connector1 = new SelectChannelConnector(); connector1.setPort(1987); connector1.setThreadPool(new QueuedThreadPool(5)); Server server = new Server(); server.setConnectors(new Connector[]{connector1}); //使用servlet处理请求 ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS); context.setContextPath("/"); context.addServlet(new ServletHolder(new NonBlockingServlet()), "/fetch"); server.setHandler(context); server.start(); server.join(); }}
A.2,实现自定义的servlets接受前端client连接,将请求信息传入队列request queue
package test;import java.io.IOException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.eclipse.jetty.continuation.Continuation;import org.eclipse.jetty.continuation.ContinuationSupport;import org.json.simple.JSONObject;import redis.clients.jedis.Jedis;public class NonBlockingServlet extends HttpServlet { /** * generated serialize number */ private static final long serialVersionUID = 3313258432391586994L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { // 用sleeptime来模拟后台工作量 String sleepTime = request.getParameter("st"); if(sleepTime == null){ sleepTime = "0"; } // 查看结果队列是否返回此连接的请求结果 Object results = request.getAttribute("results"); if (results==null) // 如果异步处理尚未返回结果 { Continuation continuation = ContinuationSupport.getContinuation(request); if(continuation.isInitial()){ // 设置连接超时时间 continuation.setTimeout(10000); response.setContentType("text/plain"); response.getWriter().flush(); HttpSession session=request.getSession(); String sid = session.getId(); Jedis jedis = new Jedis("127.0.0.1",6379); //将请求连接sessionid以及请求内容encode后传到处理队列中 JSONObject obj=new JSONObject(); obj.put("request_sid",sid); obj.put("params",sleepTime); jedis.lpush("request_queue", obj.toJSONString()); //将连接和continuation实例做个映射关系存到全局hashmap中,不确定这里是否应该加锁 PJetty.globalMap.put(sid, continuation); } // 判断是否超时 if (continuation.isExpired()) { // 返回超时Response response.getWriter().println("timeout"); response.getWriter().flush(); return; } // 挂起HTTP连接 continuation.suspend(); return; // or continuation.undispatch(); } // 连接恢复后返回结果 response.getWriter().println("Got Result:\t" + results); response.getWriter().flush(); }}
业务服务器:
B,实现后端worker.php(可以自定义worker进程数,我这里设置为5个php进程,进程数多能获取更好的并发)(用到predis库)
#!/root/bin/php<?phprequire_once("lib/Predis/Autoloader.php");function worker_thread(){ Predis\Autoloader::register(); $redis = new Predis\Client(‘tcp://127.0.0.1:6379‘); while(true){ try{ $request = $redis->brpop("request_queue", 0); } catch(Exception $e){ continue; } /** demo array(2) { [0]=> string(13) "request_queue" [1]=> string(55) "{"request_sid":"q0muxazo8k1h1k3uw85wuayh","params":"4"}" } */ $request = json_decode($request[1], true); // sleep represents work loads sleep(intval($request["params"])); $results = array("request_sid"=>$request["request_sid"], "results"=>$request["params"]); $response = json_encode($results); $redis->lpush("response_queue",$response); }}//开启多个worker进程提供服务for ($worker_nbr = 0; $worker_nbr < 5; $worker_nbr++) { $pid = pcntl_fork(); if ($pid == 0) { worker_thread(); return; }}?>
运行结果如下:
这只是一个简单的demo,为了防止redis,workers进程挂掉或者客户端异常断开,还需要做些异常处理,比如设置请求超时,捕获一些空指针等,超时需要将continuation从globalMap中剔除,防止内存得不到释放。
root # for((i=10;i>=1;i--)) ; do lynx -dump http://127.0.0.1:1987/fetch?st=$i & done[1] 14112[2] 14113[3] 14114[4] 14115[5] 14116[6] 14117[7] 14118[8] 14119[9] 14120[10] 14121root # Got Result: 3Got Result: 4Got Result: 2Got Result: 7Got Result: 1Got Result: 9Got Result: 6timeouttimeouttimeout[1] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[2] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[3] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[4] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[5] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[6] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[7] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[8] Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[9]- Done lynx -dump http://127.0.0.1:1987/fetch?st=$i[10]+ Done lynx -dump http://127.0.0.1:1987/fetch?st=$i
redis数据库中存储的内容如下,可以看出虽然经后台处理后顺序变化了,但是对应关系正确,接入服务器能够根据request_sid把结果返回给相应的用户:
redis 127.0.0.1:6379> lrange request_queue 0 15 1) "{\"request_sid\":\"igiwkwnb715aphw8uvtfa6rj\",\"params\":\"3\"}" 2) "{\"request_sid\":\"wsrglxa3h6ef19ik5i0nbiiys\",\"params\":\"2\"}" 3) "{\"request_sid\":\"tyiqoj6awj5t16ddpqusftwc8\",\"params\":\"6\"}" 4) "{\"request_sid\":\"1052tgkiyy7c31bmxjtbom7ca\",\"params\":\"5\"}" 5) "{\"request_sid\":\"17jo1xwnnkd3h1mhcqcfplrl5k\",\"params\":\"8\"}" 6) "{\"request_sid\":\"1xk521sq6vmmf6enxauwzduj9\",\"params\":\"4\"}" 7) "{\"request_sid\":\"1cxnir1slgjiq1o2n3xwznh0kk\",\"params\":\"9\"}" 8) "{\"request_sid\":\"961vf8hao3stsv4vt1qif3ws\",\"params\":\"7\"}" 9) "{\"request_sid\":\"35pfn5au6p8qdbri17p636si\",\"params\":\"10\"}"10) "{\"request_sid\":\"1ca4wy8qsfr7av0hwk8xtlqhp\",\"params\":\"1\"}"redis 127.0.0.1:6379> lrange response_queue 0 15 1) "{\"request_sid\":\"tyiqoj6awj5t16ddpqusftwc8\",\"results\":\"6\"}" 2) "{\"request_sid\":\"igiwkwnb715aphw8uvtfa6rj\",\"results\":\"3\"}" 3) "{\"request_sid\":\"wsrglxa3h6ef19ik5i0nbiiys\",\"results\":\"2\"}" 4) "{\"request_sid\":\"35pfn5au6p8qdbri17p636si\",\"results\":\"10\"}" 5) "{\"request_sid\":\"1052tgkiyy7c31bmxjtbom7ca\",\"results\":\"5\"}" 6) "{\"request_sid\":\"1cxnir1slgjiq1o2n3xwznh0kk\",\"results\":\"9\"}" 7) "{\"request_sid\":\"17jo1xwnnkd3h1mhcqcfplrl5k\",\"results\":\"8\"}" 8) "{\"request_sid\":\"961vf8hao3stsv4vt1qif3ws\",\"results\":\"7\"}" 9) "{\"request_sid\":\"1xk521sq6vmmf6enxauwzduj9\",\"results\":\"4\"}"10) "{\"request_sid\":\"1ca4wy8qsfr7av0hwk8xtlqhp\",\"results\":\"1\"}"
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