面试官:xxl-job双端是怎么进行交互的？？
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背景
最近测试环境，有一个应用一直没法关闭，只能强杀，登上服务器发现是这个应用有个线程一直监听着9999端口，排查发现是xxl-job没有正确配置，导致线程一直等待，无法正常关闭，正确配置后就正常了。用了xxl-job也挺久了，正好趁这个机会，看看xxl-job到底是怎么进行admin端和客户端交互的
源码解析
既然研究源码了，当然就选择直接拉取git代码，本地启动后就可以登录了
登录成功后，会发现官方已经提供了一个jobhandler示例，直接使用即可，点击执行，会发现它调用了/jobinfo/trigger接口
@RequestMapping("/trigger")
@ResponseBody
public ReturnT<String> triggerJob(HttpServletRequest request, int id, String executorParam, String addressList) {
// login user
XxlJobUser loginUser = (XxlJobUser) request.getAttribute(LoginService.LOGIN_IDENTITY_KEY);
// trigger
return xxlJobService.trigger(loginUser, id, executorParam, addressList);
}
前面都是一些用户信息的校验，直接来到JobTriggerPoolHelper.trigger()方法
/**
* add trigger
*/
public void addTrigger(final int jobId,
final TriggerTypeEnum triggerType,
final int failRetryCount,
final String executorShardingParam,
final String executorParam,
final String addressList) {
// 选择线程池
ThreadPoolExecutor triggerPool_ = fastTriggerPool;
// 计算超时次数
AtomicInteger jobTimeoutCount = jobTimeoutCountMap.get(jobId);
// 大于10次，则切换线程池
if (jobTimeoutCount!=null && jobTimeoutCount.get() > 10) { // job-timeout 10 times in 1 min
triggerPool_ = slowTriggerPool;
}
// trigger
triggerPool_.execute(new Runnable() {
@Override
public void run() {
long start = System.currentTimeMillis();
try {
// 执行触发器
XxlJobTrigger.trigger(jobId, triggerType, failRetryCount, executorShardingParam, executorParam, addressList);
} catch (Exception e) {
logger.error(e.getMessage(), e);
} finally {
// check timeout-count-map
long minTim_now = System.currentTimeMillis()/60000;
if (minTim != minTim_now) {
minTim = minTim_now;
jobTimeoutCountMap.clear();
}
// incr timeout-count-map
long cost = System.currentTimeMillis()-start;
if (cost > 500) { // ob-timeout threshold 500ms
AtomicInteger timeoutCount = jobTimeoutCountMap.putIfAbsent(jobId, new AtomicInteger(1));
if (timeoutCount != null) {
timeoutCount.incrementAndGet();
}
}
}
}
});
}
这里主要是使用线程池，执行方法，不得不说xxl-job对于线程池的使用是真的好，后续有时间，希望能去研究研究这个项目线程池的使用。继续调用 XxlJobTrigger.trigger()方法
public static void trigger(int jobId,
TriggerTypeEnum triggerType,
int failRetryCount,
String executorShardingParam,
String executorParam,
String addressList) {
// 获取jobhandler数据
XxlJobInfo jobInfo = XxlJobAdminConfig.getAdminConfig().getXxlJobInfoDao().loadById(jobId);
if (jobInfo == null) {
logger.warn(">>>>>>>>>>>> trigger fail, jobId invalid，jobId={}", jobId);
return;
}
// 设置执行参数
if (executorParam != null) {
jobInfo.setExecutorParam(executorParam);
}
int finalFailRetryCount = failRetryCount>=0?failRetryCount:jobInfo.getExecutorFailRetryCount();
// 获取执行器
XxlJobGroup group = XxlJobAdminConfig.getAdminConfig().getXxlJobGroupDao().load(jobInfo.getJobGroup());
// 添加地址集合
if (addressList!=null && addressList.trim().length()>0) {
group.setAddressType(1);
group.setAddressList(addressList.trim());
}
// 设置分片参数
int[] shardingParam = null;
if (executorShardingParam!=null){
String[] shardingArr = executorShardingParam.split("/");
if (shardingArr.length==2 && isNumeric(shardingArr[0]) && isNumeric(shardingArr[1])) {
shardingParam = new int[2];
shardingParam[0] = Integer.valueOf(shardingArr[0]);
shardingParam[1] = Integer.valueOf(shardingArr[1]);
}
}
// 执行分片广播
if (ExecutorRouteStrategyEnum.SHARDING_BROADCAST==ExecutorRouteStrategyEnum.match(jobInfo.getExecutorRouteStrategy(), null)
&& group.getRegistryList()!=null && !group.getRegistryList().isEmpty()
&& shardingParam==null) {
for (int i = 0; i < group.getRegistryList().size(); i++) {
processTrigger(group, jobInfo, finalFailRetryCount, triggerType, i, group.getRegistryList().size());
}
}
// 普通广播
else {
if (shardingParam == null) {
shardingParam = new int[]{0, 1};
}
processTrigger(group, jobInfo, finalFailRetryCount, triggerType, shardingParam[0], shardingParam[1]);
}
}
这里主要是获取到handler和执行器的各种参数，用于后续的请求，执行processTrigger()方法，这里代码就比较长，稍微省略初始化数据的代码
private static void processTrigger(XxlJobGroup group, XxlJobInfo jobInfo, int finalFailRetryCount, TriggerTypeEnum triggerType, int index, int total){
// param
ExecutorBlockStrategyEnum blockStrategy = ExecutorBlockStrategyEnum.match(jobInfo.getExecutorBlockStrategy(), ExecutorBlockStrategyEnum.SERIAL_EXECUTION); // block strategy
ExecutorRouteStrategyEnum executorRouteStrategyEnum = ExecutorRouteStrategyEnum.match(jobInfo.getExecutorRouteStrategy(), null); // route strategy
String shardingParam = (ExecutorRouteStrategyEnum.SHARDING_BROADCAST==executorRouteStrategyEnum)?String.valueOf(index).concat("/").concat(String.valueOf(total)):null;
//日志记录
// 初始化执行参数
// 初始化远程地址
// 执行远程请求
ReturnT<String> triggerResult = null;
if (address != null) {
triggerResult = runExecutor(triggerParam, address);
} else {
triggerResult = new ReturnT<String>(ReturnT.FAIL_CODE, null);
}
// 5、解析请求结果
StringBuffer triggerMsgSb = new StringBuffer();
triggerMsgSb.append(I18nUtil.getString("jobconf_trigger_type")).append("：").append(triggerType.getTitle());
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobconf_trigger_admin_adress")).append("：").append(IpUtil.getIp());
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobconf_trigger_exe_regtype")).append("：")
.append( (group.getAddressType() == 0)?I18nUtil.getString("jobgroup_field_addressType_0"):I18nUtil.getString("jobgroup_field_addressType_1") );
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobconf_trigger_exe_regaddress")).append("：").append(group.getRegistryList());
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobinfo_field_executorRouteStrategy")).append("：").append(executorRouteStrategyEnum.getTitle());
if (shardingParam != null) {
triggerMsgSb.append("("+shardingParam+")");
}
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobinfo_field_executorBlockStrategy")).append("：").append(blockStrategy.getTitle());
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobinfo_field_timeout")).append("：").append(jobInfo.getExecutorTimeout());
triggerMsgSb.append("<br>").append(I18nUtil.getString("jobinfo_field_executorFailRetryCount")).append("：").append(finalFailRetryCount);
triggerMsgSb.append("<br><br><span style="color:#00c0ef;" > >>>>>>>>>>>"+ I18nUtil.getString("jobconf_trigger_run") +"<<<<<<<<<<< </span><br>")
.append((routeAddressResult!=null&&routeAddressResult.getMsg()!=null)?routeAddressResult.getMsg()+"<br><br>":"").append(triggerResult.getMsg()!=null?triggerResult.getMsg():"");
// 6、日志记录
}
初始化各种参数后，调用runExecutor()方法
/**
* run executor
* @param triggerParam
* @param address
* @return
*/
public static ReturnT<String> runExecutor(TriggerParam triggerParam, String address){
ReturnT<String> runResult = null;
try {
// 获取请求执行器
ExecutorBiz executorBiz = XxlJobScheduler.getExecutorBiz(address);
runResult = executorBiz.run(triggerParam);
} catch (Exception e) {
logger.error(">>>>>>>>>>> xxl-job trigger error, please check if the executor[{}] is running.", address, e);
runResult = new ReturnT<String>(ReturnT.FAIL_CODE, ThrowableUtil.toString(e));
}
StringBuffer runResultSB = new StringBuffer(I18nUtil.getString("jobconf_trigger_run") + "：");
runResultSB.append("<br>address：").append(address);
runResultSB.append("<br>code：").append(runResult.getCode());
runResultSB.append("<br>msg：").append(runResult.getMsg());
runResult.setMsg(runResultSB.toString());
return runResult;
}
// 根据地址缓存
public static ExecutorBiz getExecutorBiz(String address) throws Exception {
// valid
if (address==null || address.trim().length()==0) {
return null;
}
// load-cache
address = address.trim();
ExecutorBiz executorBiz = executorBizRepository.get(address);
if (executorBiz != null) {
return executorBiz;
}
// set-cache
executorBiz = new ExecutorBizClient(address, XxlJobAdminConfig.getAdminConfig().getAccessToken());
executorBizRepository.put(address, executorBiz);
return executorBiz;
}
点开ExecutorBiz，会发现有两个实现类，对应了admin和jobhandler客户端 
点开ExecutorBizClient.run方法，会发现他其实是发送了一个http请求地址就是addressurl/run
@Override
public ReturnT<String> run(TriggerParam triggerParam) {
return XxlJobRemotingUtil.postBody(addressUrl + "run", accessToken, timeout, triggerParam, String.class);
}
问题又来了，客户端是怎么接收的呢？ demo示例已经告诉我们答案了
public void initXxlJobExecutor() {
// load executor prop
Properties xxlJobProp = loadProperties("xxl-job-executor.properties");
// init executor
xxlJobExecutor = new XxlJobSimpleExecutor();
xxlJobExecutor.setAdminAddresses(xxlJobProp.getProperty("xxl.job.admin.addresses"));
xxlJobExecutor.setAccessToken(xxlJobProp.getProperty("xxl.job.accessToken"));
xxlJobExecutor.setAppname(xxlJobProp.getProperty("xxl.job.executor.appname"));
xxlJobExecutor.setAddress(xxlJobProp.getProperty("xxl.job.executor.address"));
xxlJobExecutor.setIp(xxlJobProp.getProperty("xxl.job.executor.ip"));
xxlJobExecutor.setPort(Integer.valueOf(xxlJobProp.getProperty("xxl.job.executor.port")));
xxlJobExecutor.setLogPath(xxlJobProp.getProperty("xxl.job.executor.logpath"));
xxlJobExecutor.setLogRetentionDays(Integer.valueOf(xxlJobProp.getProperty("xxl.job.executor.logretentiondays")));
// registry job bean
xxlJobExecutor.setXxlJobBeanList(Arrays.asList(new SampleXxlJob()));
// start executor
try {
xxlJobExecutor.start();
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
点开start，之后会发现会调用initEmbedServer方法
private void initEmbedServer(String address, String ip, int port, String appname, String accessToken) throws Exception {
// fill ip port
port = port>0?port: NetUtil.findAvailablePort(9999);
ip = (ip!=null&&ip.trim().length()>0)?ip: IpUtil.getIp();
// generate address
if (address==null || address.trim().length()==0) {
String ip_port_address = IpUtil.getIpPort(ip, port); // registry-address：default use address to registry , otherwise use ip:port if address is null
address = "http://{ip_port}/".replace("{ip_port}", ip_port_address);
}
// accessToken
if (accessToken==null || accessToken.trim().length()==0) {
logger.warn(">>>>>>>>>>> xxl-job accessToken is empty. To ensure system security, please set the accessToken.");
}
// start
embedServer = new EmbedServer();
embedServer.start(address, port, appname, accessToken);
}
继续查看embedServer.start()方法
public void start(final String address, final int port, final String appname, final String accessToken) {
executorBiz = new ExecutorBizImpl();
thread = new Thread(new Runnable() {
@Override
public void run() {
// param
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
ThreadPoolExecutor bizThreadPool = new ThreadPoolExecutor(
0,
200,
60L,
TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(2000),
new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
return new Thread(r, "xxl-job, EmbedServer bizThreadPool-" + r.hashCode());
}
},
new RejectedExecutionHandler() {
@Override
public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
throw new RuntimeException("xxl-job, EmbedServer bizThreadPool is EXHAUSTED!");
}
});
try {
// start server
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel channel) throws Exception {
channel.pipeline()
.addLast(new IdleStateHandler(0, 0, 30 * 3, TimeUnit.SECONDS)) // beat 3N, close if idle
.addLast(new HttpServerCodec())
.addLast(new HttpObjectAggregator(5 * 1024 * 1024)) // 注册自定义请求处理器，处理request请求
.addLast(new EmbedHttpServerHandler(executorBiz, accessToken, bizThreadPool));
}
})
.childOption(ChannelOption.SO_KEEPALIVE, true);
// bind
ChannelFuture future = bootstrap.bind(port).sync();
。。。。。
}
看到这里用过netty的朋友应该会感觉很熟悉，是的，它就是在客户端启动了一个http服务，监听请求，注册了一个处理器去处理admin的请求
@Override
protected void channelRead0(final ChannelHandlerContext ctx, FullHttpRequest msg) throws Exception {
// request parse
//final byte[] requestBytes = ByteBufUtil.getBytes(msg.content()); // byteBuf.toString(io.netty.util.CharsetUtil.UTF_8);
String requestData = msg.content().toString(CharsetUtil.UTF_8);
String uri = msg.uri();
HttpMethod httpMethod = msg.method();
boolean keepAlive = HttpUtil.isKeepAlive(msg);
String accessTokenReq = msg.headers().get(XxlJobRemotingUtil.XXL_JOB_ACCESS_TOKEN);
// invoke
bizThreadPool.execute(new Runnable() {
@Override
public void run() {
// 处理请求，并返回结果
Object responseObj = process(httpMethod, uri, requestData, accessTokenReq);
// to json
String responseJson = GsonTool.toJson(responseObj);
// write response
writeResponse(ctx, keepAlive, responseJson);
}
});
}
查看process方法
private Object process(HttpMethod httpMethod, String uri, String requestData, String accessTokenReq) {
// valid
if (HttpMethod.POST != httpMethod) {
return new ReturnT<String>(ReturnT.FAIL_CODE, "invalid request, HttpMethod not support.");
}
if (uri == null || uri.trim().length() == 0) {
return new ReturnT<String>(ReturnT.FAIL_CODE, "invalid request, uri-mapping empty.");
}
if (accessToken != null
&& accessToken.trim().length() > 0
&& !accessToken.equals(accessTokenReq)) {
return new ReturnT<String>(ReturnT.FAIL_CODE, "The access token is wrong.");
}
// 对应的请求路径
try {
switch (uri) {
case "/beat":
return executorBiz.beat();
case "/idleBeat":
IdleBeatParam idleBeatParam = GsonTool.fromJson(requestData, IdleBeatParam.class);
return executorBiz.idleBeat(idleBeatParam);
case "/run":
TriggerParam triggerParam = GsonTool.fromJson(requestData, TriggerParam.class);
return executorBiz.run(triggerParam);
case "/kill":
KillParam killParam = GsonTool.fromJson(requestData, KillParam.class);
return executorBiz.kill(killParam);
case "/log":
LogParam logParam = GsonTool.fromJson(requestData, LogParam.class);
return executorBiz.log(logParam);
default:
return new ReturnT<String>(ReturnT.FAIL_CODE, "invalid request, uri-mapping(" + uri + ") not found.");
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
return new ReturnT<String>(ReturnT.FAIL_CODE, "request error:" + ThrowableUtil.toString(e));
}
}
看到这里，整体流程就比较清晰了，admin是通过http请求的方式，请求客户端，客户端会启动一个服务器，去处理对应的http请求
总结
宏观看，xxl-job主要就是通过http的方式进行admin端和客户端的交互，所以我们每次引入xxl-job的时候都要指定地址和端口，因为它需要通过netty创建一个建议的服务器进行请求的处理
转载自:https://juejin.cn/post/7377283135127781415