从官方将源码下载下来，当前发布版本为2.2.0，该版本下载的为最新版本2.2.1,。代码相差不大，接下来对xxl-job进行一步一步拆解

github地址 GitHub - xuxueli/xxl-job: A distributed task scheduling framework.（分布式任务调度平台XXL-JOB）

码云地址 xxl-job: 一个分布式任务调度平台，其核心设计目标是开发迅速、学习简单、轻量级、易扩展。现已开放源代码并接入多家公司线上产品线，开箱即用。

该框架有如下优点

1、使用层面

简单、好用，源码易读，修改简单

2、功能层面

1、有可视化界面进行操作，可以集中化管理任务

2、通过可视化可以对任务的管理，执行，调度，任务生命周期管理

3、任务执行支持手动和corn表达式定时触发

4、任务调度支持配置任务链以及任务执行失败的阻断策略

5、任务执行时间，执行信息等记录，可以更好地分析任务瓶颈以及执行分布时间

等等

1、xxl目录结构

xxl-job的目录如下

1.1 xxl-job-admin

该目录为调度中心源码,包括任务的管理，执行，调度，以及运行监控报表。喏，就下面这个

1.2 xxl-job-core

该代码为服务集成的核心源码包，包括重要注解，执行器等。

1.3 xxl-job-executor-samples

该包为服务集成测试demo，支持frameless，jfinal，spring，SpringBoot等多个框架集成。

2、架构设计

2.1 整体架构设计

通过服务注册的方式，将job注册到任务调度中心，通过调度中心进行统一的任务管理

2.2 服务集成

以SpringBoot集成xxl-job为例，集成直接运行demo即可，可以参考01.XXL-JOB这个文章。

1、配置文件

# web port spring web容器端口
server.port=8083
# no web
#spring.main.web-environment=false
# log config
logging.config=classpath:logback.xml
### xxl-job注册中心地址
xxl.job.admin.addresses=http://127.0.0.1:8080/xxl-job-admin
### xxl-job access token
xxl.job.accessToken=
### xxl-job 执行器名称
xxl.job.executor.appname=omsJob
### xxl-job executor 执行器ip
xxl.job.executor.ip=
### xxl-job executor 执行器端口
xxl.job.executor.port=9999
### xxl-job executor log-path 日志配置
xxl.job.executor.logpath=/data/applogs/xxl-job/jobhandler
### xxl-job executor log-retention-days 日志定时清理时间
xxl.job.executor.logretentiondays=30

2、初始化执行器

@Bean
public XxlJobSpringExecutor xxlJobExecutor() {
logger.info(">>>>>>>>>>> xxl-job config init.");
XxlJobSpringExecutor xxlJobSpringExecutor = new XxlJobSpringExecutor();
xxlJobSpringExecutor.setAdminAddresses(adminAddresses);
xxlJobSpringExecutor.setAppname(appname);
xxlJobSpringExecutor.setAddress(address);
xxlJobSpringExecutor.setIp(ip);
xxlJobSpringExecutor.setPort(port);
xxlJobSpringExecutor.setAccessToken(accessToken);
xxlJobSpringExecutor.setLogPath(logPath);
xxlJobSpringExecutor.setLogRetentionDays(logRetentionDays);
return xxlJobSpringExecutor;
}

3、使用xxl-job注解配置任务

/**
* 1、简单任务示例（Bean模式）
*/
@XxlJob("demoJobHandler")
public ReturnT<String> demoJobHandler(String param) throws Exception {
XxlJobLogger.log("XXL-JOB, Hello World.");
for (int i = 0; i < 5; i++) {
XxlJobLogger.log("beat at:" + i);
TimeUnit.SECONDS.sleep(2);
}
return ReturnT.SUCCESS;
}

4、启动成功后，服务会开启两个端口，一个是业务端口，一个是调度中心下发job执行的端口。（此处要优化，服务和job触发其实使用一个端口即可）

3、启动源码分析

1、服务启动流程

@Bean
public XxlJobSpringExecutor xxlJobExecutor() {
logger.info(">>>>>>>>>>> xxl-job config init.");
XxlJobSpringExecutor xxlJobSpringExecutor = new XxlJobSpringExecutor();
xxlJobSpringExecutor.setAdminAddresses(adminAddresses);
xxlJobSpringExecutor.setAppname(appname);
xxlJobSpringExecutor.setAddress(address);
xxlJobSpringExecutor.setIp(ip);
xxlJobSpringExecutor.setPort(port);
xxlJobSpringExecutor.setAccessToken(accessToken);
xxlJobSpringExecutor.setLogPath(logPath);
xxlJobSpringExecutor.setLogRetentionDays(logRetentionDays);
return xxlJobSpringExecutor;
}

服务主要启动是初始化XxlJobSpringExecutor这个bean对象，该对象定义了执行器xxlJobSpringExecutor的相关配置，如注册中心地址，服务提供地址，以及授权token等。该对象类图如下，

XxlJobSpringExecutor执行器继承XxlJobExecutor并实现Spring的ApplicationContextAware等类，对该bean进行了增强。主要核心类为XxlJobExecutor。

因为继承SmartInitializingSingleton，所以bean初始化完成之后会执行afterSingletonsInstantiated方法，该类主要为initJobHandlerMethodRepository这个方法，用于扫描xxl-job注解，进行任务加载和管理

// start
@Override
public void afterSingletonsInstantiated() {
// 扫描xxl-job注解，进行任务加载和管理
initJobHandlerMethodRepository(applicationContext);
// refresh GlueFactory
GlueFactory.refreshInstance(1);
// super start
try {
super.start();
} catch (Exception e) {
throw new RuntimeException(e);
}
}

initJobHandlerMethodRepository方法主要如下

该方法主要是通过获取Spring管理的容器bean，然后扫描带有xxljob注解的方法，将他们保存在jobHandlerRepository对象中

private void initJobHandlerMethodRepository(ApplicationContext applicationContext) {
if (applicationContext == null) {
return;
}
// 扫描Spring管理的bean
String[] beanDefinitionNames = applicationContext.getBeanNamesForType(Object.class, false, true);
for (String beanDefinitionName : beanDefinitionNames) {
Object bean = applicationContext.getBean(beanDefinitionName);
Map<Method, XxlJob> annotatedMethods = null; // referred to ：org.springframework.context.event.EventListenerMethodProcessor.processBean
try {
annotatedMethods = MethodIntrospector.selectMethods(bean.getClass(),
new MethodIntrospector.MetadataLookup<XxlJob>() {
@Override
public XxlJob inspect(Method method) {
// 获取注解为XxlJob的方法，并保存在annotatedMethods
return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);
}
});
} catch (Throwable ex) {
logger.error("xxl-job method-jobhandler resolve error for bean[" + beanDefinitionName + "].", ex);
}
if (annotatedMethods==null || annotatedMethods.isEmpty()) {
continue;
}
//获取方法属性，并存储在jobHandlerRepository对象中
for (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {
Method method = methodXxlJobEntry.getKey();
XxlJob xxlJob = methodXxlJobEntry.getValue();
if (xxlJob == null) {
continue;
}
String name = xxlJob.value();
if (name.trim().length() == 0) {
throw new RuntimeException("xxl-job method-jobhandler name invalid, for[" + bean.getClass() + "#" + method.getName() + "] .");
}
if (loadJobHandler(name) != null) {
throw new RuntimeException("xxl-job jobhandler[" + name + "] naming conflicts.");
}
// execute method
if (!(method.getParameterTypes().length == 1 && method.getParameterTypes()[0].isAssignableFrom(String.class))) {
throw new RuntimeException("xxl-job method-jobhandler param-classtype invalid, for[" + bean.getClass() + "#" + method.getName() + "] , " +
"The correct method format like \" public ReturnT<String> execute(String param) \" .");
}
if (!method.getReturnType().isAssignableFrom(ReturnT.class)) {
throw new RuntimeException("xxl-job method-jobhandler return-classtype invalid, for[" + bean.getClass() + "#" + method.getName() + "] , " +
"The correct method format like \" public ReturnT<String> execute(String param) \" .");
}
method.setAccessible(true);
// init and destory
Method initMethod = null;
Method destroyMethod = null;
if (xxlJob.init().trim().length() > 0) {
try {
initMethod = bean.getClass().getDeclaredMethod(xxlJob.init());
initMethod.setAccessible(true);
} catch (NoSuchMethodException e) {
throw new RuntimeException("xxl-job method-jobhandler initMethod invalid, for[" + bean.getClass() + "#" + method.getName() + "] .");
}
}
if (xxlJob.destroy().trim().length() > 0) {
try {
destroyMethod = bean.getClass().getDeclaredMethod(xxlJob.destroy());
destroyMethod.setAccessible(true);
} catch (NoSuchMethodException e) {
throw new RuntimeException("xxl-job method-jobhandler destroyMethod invalid, for[" + bean.getClass() + "#" + method.getName() + "] .");
}
}
// registry jobhandler
//将任务存储在jobHandlerRepository对象中，后续下发任务使用
registJobHandler(name, new MethodJobHandler(bean, method, initMethod, destroyMethod));
}
}

之后执行super.start()，执行父类XxlJobExecutor的start方法。该方法主要有日志初始化，日志清理任务初始化，RPC调用触发器回调线程启动，调度中心列表初始化以及执行器端口初始化。

public void start() throws Exception { // init logpath
//初始化任务执行日志路径
XxlJobFileAppender.initLogPath(logPath);
// 日志定时清理任务
JobLogFileCleanThread.getInstance().start(logRetentionDays);
// 初始化触发器回调线程(用RPC回调调度中心接口)
TriggerCallbackThread.getInstance().start();
//初始化调度中心列表
initAdminBizList( adminAddresses, accessToken);
// init executor-server 执行器端口启动
initEmbedServer(address, ip, port, appname, accessToken);
}

 XxlJobFileAppender.initLogPath(logPath)和JobLogFileCleanThread.getInstance().start(logRetentionDays)主要对执行日志进行初始化，就不多解释了，直接往下看。

TriggerCallbackThread.getInstance().start();

public void start() {
// 调度中心注册表会否为空
if (XxlJobExecutor.getAdminBizList() == null) {
logger.warn(">>>>>>>>>>> xxl-job, executor callback config fail, adminAddresses is null.");
return;
}
// callback
triggerCallbackThread = new Thread(new Runnable() {
@Override
public void run() {
// 监听阻塞队列
while(!toStop){
try {
HandleCallbackParam callback = getInstance().callBackQueue.take();
if (callback != null) {
// 组装callback返回的参数
List<HandleCallbackParam> callbackParamList = new ArrayList<HandleCallbackParam>();
int drainToNum = getInstance().callBackQueue.drainTo(callbackParamList);
callbackParamList.add(callback);
// 执行回调
if (callbackParamList!=null && callbackParamList.size()>0) {
doCallback(callbackParamList);
}
}
} catch (Exception e) {
if (!toStop) {
logger.error(e.getMessage(), e);
}
}
}
// last callback
try {
List<HandleCallbackParam> callbackParamList = new ArrayList<HandleCallbackParam>();
int drainToNum = getInstance().callBackQueue.drainTo(callbackParamList);
if (callbackParamList!=null && callbackParamList.size()>0) {
doCallback(callbackParamList);
}
} catch (Exception e) {
if (!toStop) {
logger.error(e.getMessage(), e);
}
}
logger.info(">>>>>>>>>>> xxl-job, executor callback thread destory.");
}
});
triggerCallbackThread.setDaemon(true);
triggerCallbackThread.setName("xxl-job, executor TriggerCallbackThread");
triggerCallbackThread.start();
// retry
triggerRetryCallbackThread = new Thread(new Runnable() {
@Override
public void run() {
while(!toStop){
try {
retryFailCallbackFile();
} catch (Exception e) {
if (!toStop) {
logger.error(e.getMessage(), e);
}
}
try {
TimeUnit.SECONDS.sleep(RegistryConfig.BEAT_TIMEOUT);
} catch (InterruptedException e) {
if (!toStop) {
logger.error(e.getMessage(), e);
}
}
}
logger.info(">>>>>>>>>>> xxl-job, executor retry callback thread destory.");
}
});
triggerRetryCallbackThread.setDaemon(true);
triggerRetryCallbackThread.start();
}

 doCallback(callbackParamList)如下

/**
* do callback, will retry if error
* @param callbackParamList
*/
private void doCallback(List<HandleCallbackParam> callbackParamList){
boolean callbackRet = false;
// 向所有的调度中心发送回调信息
for (AdminBiz adminBiz: XxlJobExecutor.getAdminBizList()) {
try {
//本质上是调用注册中心的api/callback接口。记录调用结果。
ReturnT<String> callbackResult = adminBiz.callback(callbackParamList);
if (callbackResult!=null && ReturnT.SUCCESS_CODE == callbackResult.getCode()) {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback finish.");
callbackRet = true;
break;
} else {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback fail, callbackResult:" + callbackResult);
}
} catch (Exception e) {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback error, errorMsg:" + e.getMessage());
}
}
if (!callbackRet) {
appendFailCallbackFile(callbackParamList);
}
}

adminBiz.callback(callbackParamList)

调用注册中心api接口

@Override
public ReturnT<String> callback(List<HandleCallbackParam> callbackParamList) {
return XxlJobRemotingUtil.postBody(addressUrl+"api/callback", accessToken, timeout, callbackParamList, String.class);

initAdminBizList( adminAddresses, accessToken); 初始化注册中心列表，用于后期和注册中心交互

//扫描xxl.job.admin.addresses配置，将他们加入注册中心列表adminBizList对象中。用于后期发送回调
private void initAdminBizList(String adminAddresses, String accessToken) throws Exception {
if (adminAddresses!=null && adminAddresses.trim().length()>0) {
for (String address: adminAddresses.trim().split(",")) {
if (address!=null && address.trim().length()>0) {
AdminBiz adminBiz = new AdminBizClient(address.trim(), accessToken);
if (adminBizList == null) {
adminBizList = new ArrayList<AdminBiz>();
}
adminBizList.add(adminBiz);
}
}
}
}

// init executor-server
initEmbedServer(address, ip, port, appname, accessToken);<核心>

//初始化xxljob执行器服务
private void initEmbedServer(String address, String ip, int port, String appname, String accessToken) throws Exception {
//初始化ip和端口，如果没有ip则自动获取本地ip
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);
}
// 启动服务
embedServer = new EmbedServer();
embedServer.start(address, port, appname, accessToken);
}

embedServer.start(address, port, appname, accessToken); 本质上是一个Netty服务，标准的Netty服务启动，我们只看EmbedHttpServerHandler，Netty处理请求的handler

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-rpc, 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)) // merge request & reponse to FULL
.addLast(new EmbedHttpServerHandler(executorBiz, accessToken, bizThreadPool));
}
})
.childOption(ChannelOption.SO_KEEPALIVE, true);
// bind
ChannelFuture future = bootstrap.bind(port).sync();
logger.info(">>>>>>>>>>> xxl-job remoting server start success, nettype = {}, port = {}", EmbedServer.class, port);
//注册到调度中心
startRegistry(appname, address);
// wait util stop
future.channel().closeFuture().sync();
} catch (InterruptedException e) {
if (e instanceof InterruptedException) {
logger.info(">>>>>>>>>>> xxl-job remoting server stop.");
} else {
logger.error(">>>>>>>>>>> xxl-job remoting server error.", e);
}
} finally {
// stop
try {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
}
});
thread.setDaemon(true); // daemon, service jvm, user thread leave >>> daemon leave >>> jvm leave
thread.start();
}

public static class EmbedHttpServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
private static final Logger logger = LoggerFactory.getLogger(EmbedHttpServerHandler.class);
private ExecutorBiz executorBiz; //执行器
private String accessToken; //token
private ThreadPoolExecutor bizThreadPool;//执行器线程池
public EmbedHttpServerHandler(ExecutorBiz executorBiz, String accessToken, ThreadPoolExecutor bizThreadPool) {
this.executorBiz = executorBiz;
this.accessToken = accessToken;
this.bizThreadPool = bizThreadPool;
}
@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);//获取请求数据
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
Object responseObj = process(httpMethod, uri, requestData, accessTokenReq);
// 格式化为JSON
String responseJson = GsonTool.toJson(responseObj);
// 写回客户端
writeResponse(ctx, keepAlive, responseJson);
}
});
}
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.");
}
// services mapping
try {
//接收注册中心请求接口处理
if ("/beat".equals(uri)) {
return executorBiz.beat();
} else if ("/idleBeat".equals(uri)) {
IdleBeatParam idleBeatParam = GsonTool.fromJson(requestData, IdleBeatParam.class);
return executorBiz.idleBeat(idleBeatParam);
} else if ("/run".equals(uri)) { //注册中心执行接口
TriggerParam triggerParam = GsonTool.fromJson(requestData, TriggerParam.class);
return executorBiz.run(triggerParam);
} else if ("/kill".equals(uri)) {
KillParam killParam = GsonTool.fromJson(requestData, KillParam.class);
return executorBiz.kill(killParam);
} else if ("/log".equals(uri)) {
LogParam logParam = GsonTool.fromJson(requestData, LogParam.class);
return executorBiz.log(logParam);
} else {
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));
}

我们主要看下run方法的执行过程

@Override
public ReturnT<String> run(TriggerParam triggerParam) {
// 根据jobid加载对应的job执行信息，第一次执行为null
JobThread jobThread = XxlJobExecutor.loadJobThread(triggerParam.getJobId());
IJobHandler jobHandler = jobThread!=null?jobThread.getHandler():null;//根绝jobThread获取job处理handler
String removeOldReason = null;
// valid：jobHandler + jobThread
GlueTypeEnum glueTypeEnum = GlueTypeEnum.match(triggerParam.getGlueType()); //获取任务类型
if (GlueTypeEnum.BEAN == glueTypeEnum) {
// new jobhandler
IJobHandler newJobHandler = XxlJobExecutor.loadJobHandler(triggerParam.getExecutorHandler());//获取任务的执行器
// 校验新老job是否一致，不一致将老的进行初始化。有可能任务更新。通过jobid获取的是老的
if (jobThread!=null && jobHandler != newJobHandler) {
// change handler, need kill old thread
removeOldReason = "change jobhandler or glue type, and terminate the old job thread.";
jobThread = null;
jobHandler = null;
}
// valid handler
if (jobHandler == null) {
jobHandler = newJobHandler; //将新处理handler赋值给老的
if (jobHandler == null) {
return new ReturnT<String>(ReturnT.FAIL_CODE, "job handler [" + triggerParam.getExecutorHandler() + "] not found.");
}
}
} else if (GlueTypeEnum.GLUE_GROOVY == glueTypeEnum) {
// valid old jobThread
if (jobThread != null &&
!(jobThread.getHandler() instanceof GlueJobHandler
&& ((GlueJobHandler) jobThread.getHandler()).getGlueUpdatetime()==triggerParam.getGlueUpdatetime() )) {
// change handler or gluesource updated, need kill old thread
removeOldReason = "change job source or glue type, and terminate the old job thread.";
jobThread = null;
jobHandler = null;
}
if (jobHandler == null) {
try {
IJobHandler originJobHandler = GlueFactory.getInstance().loadNewInstance(triggerParam.getGlueSource());
jobHandler = new GlueJobHandler(originJobHandler, triggerParam.getGlueUpdatetime());
} catch (Exception e) {
logger.error(e.getMessage(), e);
return new ReturnT<String>(ReturnT.FAIL_CODE, e.getMessage());
}
}
} else if (glueTypeEnum!=null && glueTypeEnum.isScript()) {
// valid old jobThread
if (jobThread != null &&
!(jobThread.getHandler() instanceof ScriptJobHandler
&& ((ScriptJobHandler) jobThread.getHandler()).getGlueUpdatetime()==triggerParam.getGlueUpdatetime() )) {
// change script or gluesource updated, need kill old thread
removeOldReason = "change job source or glue type, and terminate the old job thread.";
jobThread = null;
jobHandler = null;
}
// valid handler
if (jobHandler == null) {
jobHandler = new ScriptJobHandler(triggerParam.getJobId(), triggerParam.getGlueUpdatetime(), triggerParam.getGlueSource(), GlueTypeEnum.match(triggerParam.getGlueType()));
}
} else {
return new ReturnT<String>(ReturnT.FAIL_CODE, "glueType[" + triggerParam.getGlueType() + "] is not valid.");
}
// executor block strategy
if (jobThread != null) {
ExecutorBlockStrategyEnum blockStrategy = ExecutorBlockStrategyEnum.match(triggerParam.getExecutorBlockStrategy(), null);
if (ExecutorBlockStrategyEnum.DISCARD_LATER == blockStrategy) {
// discard when running
if (jobThread.isRunningOrHasQueue()) {
return new ReturnT<String>(ReturnT.FAIL_CODE, "block strategy effect："+ExecutorBlockStrategyEnum.DISCARD_LATER.getTitle());
}
} else if (ExecutorBlockStrategyEnum.COVER_EARLY == blockStrategy) {
// kill running jobThread
if (jobThread.isRunningOrHasQueue()) {
removeOldReason = "block strategy effect：" + ExecutorBlockStrategyEnum.COVER_EARLY.getTitle();
jobThread = null;
}
} else {
// just queue trigger
}
}
// 如果jobThread 为null，则将任务信息注册到jobThreadRepository对象进行缓存，并启动线程
if (jobThread == null) {
jobThread = XxlJobExecutor.registJobThread(triggerParam.getJobId(), jobHandler, removeOldReason);
}
//将任务推送到自己现成的任务队列中区
ReturnT<String> pushResult = jobThread.pushTriggerQueue(triggerParam);
return pushResult;
}

看下registJobThread方法，该方法主要是根据任务信息，创建一个jobThread，之后启动该线程。然后将其缓存到jobThreadRepository中。如果存在老的任务，则将老的任务停掉。

public static JobThread registJobThread(int jobId, IJobHandler handler, String removeOldReason){
JobThread newJobThread = new JobThread(jobId, handler);//创建新得jobThread对象
newJobThread.start();//启动线程
logger.info(">>>>>>>>>>> xxl-job regist JobThread success, jobId:{}, handler:{}", new Object[]{jobId, handler});
//将新的jobThread放入map中，并弹出老的。
JobThread oldJobThread = jobThreadRepository.put(jobId, newJobThread); // putIfAbsent | oh my god, map's put method return the old value!!!
if (oldJobThread != null) {
//将老的停掉
oldJobThread.toStop(removeOldReason);
oldJobThread.interrupt();
}
return newJobThread;
}

该线程执行如下，主要就是获取队列中的任务，然后通过新建FutureTask线程执行任务。之后将执行结果推到TriggerCallbackThread的队列中。通过TriggerCallbackThread推到任务调度中心，进行记录结果信息。

@Override
public void run() {
// init
try {
handler.init();
} catch (Throwable e) {
logger.error(e.getMessage(), e);
}
// execute
while(!toStop){
running = false;
idleTimes++;
TriggerParam triggerParam = null;
ReturnT<String> executeResult = null;
try {
// to check toStop signal, we need cycle, so wo cannot use queue.take(), instand of poll(timeout)
//弹出队列任务
triggerParam = triggerQueue.poll(3L, TimeUnit.SECONDS);
if (triggerParam!=null) {
running = true;
idleTimes = 0;
triggerLogIdSet.remove(triggerParam.getLogId());
// log filename, like "logPath/yyyy-MM-dd/9999.log"
String logFileName = XxlJobFileAppender.makeLogFileName(new Date(triggerParam.getLogDateTime()), triggerParam.getLogId());
XxlJobContext.setXxlJobContext(new XxlJobContext(
triggerParam.getLogId(),
logFileName,
triggerParam.getBroadcastIndex(),
triggerParam.getBroadcastTotal()));
// execute
XxlJobLogger.log("<br>----------- xxl-job job execute start -----------<br>----------- Param:" + triggerParam.getExecutorParams());
if (triggerParam.getExecutorTimeout() > 0) {
// limit timeout
Thread futureThread = null;
try {
final TriggerParam triggerParamTmp = triggerParam;
//创建futureTask线程任务，并执行
FutureTask<ReturnT<String>> futureTask = new FutureTask<ReturnT<String>>(new Callable<ReturnT<String>>() {
@Override
public ReturnT<String> call() throws Exception {
return handler.execute(triggerParamTmp.getExecutorParams());
}
});
futureThread = new Thread(futureTask);
futureThread.start();
//获取执行结果
executeResult = futureTask.get(triggerParam.getExecutorTimeout(), TimeUnit.SECONDS);
} catch (TimeoutException e) {
XxlJobLogger.log("<br>----------- xxl-job job execute timeout");
XxlJobLogger.log(e);
executeResult = new ReturnT<String>(IJobHandler.FAIL_TIMEOUT.getCode(), "job execute timeout ");
} finally {
futureThread.interrupt();
}
} else {
// just execute
executeResult = handler.execute(triggerParam.getExecutorParams());
}
if (executeResult == null) {
executeResult = IJobHandler.FAIL;
} else {
executeResult.setMsg(
(executeResult!=null&&executeResult.getMsg()!=null&&executeResult.getMsg().length()>50000)
?executeResult.getMsg().substring(0, 50000).concat("...")
:executeResult.getMsg());
executeResult.setContent(null); // limit obj size
}
XxlJobLogger.log("<br>----------- xxl-job job execute end(finish) -----------<br>----------- ReturnT:" + executeResult);
} else {
if (idleTimes > 30) {
if(triggerQueue.size() == 0) { // avoid concurrent trigger causes jobId-lost
XxlJobExecutor.removeJobThread(jobId, "excutor idel times over limit.");
}
}
}
} catch (Throwable e) {
if (toStop) {
XxlJobLogger.log("<br>----------- JobThread toStop, stopReason:" + stopReason);
}
StringWriter stringWriter = new StringWriter();
e.printStackTrace(new PrintWriter(stringWriter));
String errorMsg = stringWriter.toString();
executeResult = new ReturnT<String>(ReturnT.FAIL_CODE, errorMsg);
XxlJobLogger.log("<br>----------- JobThread Exception:" + errorMsg + "<br>----------- xxl-job job execute end(error) -----------");
} finally {
//结果添加到回调队列中
if(triggerParam != null) {
// callback handler info
if (!toStop) {
// commonm
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(triggerParam.getLogId(), triggerParam.getLogDateTime(), executeResult));
} else {
// is killed
ReturnT<String> stopResult = new ReturnT<String>(ReturnT.FAIL_CODE, stopReason + " [job running, killed]");
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(triggerParam.getLogId(), triggerParam.getLogDateTime(), stopResult));
}
}
}
}
// callback trigger request in queue
while(triggerQueue !=null && triggerQueue.size()>0){
TriggerParam triggerParam = triggerQueue.poll();
if (triggerParam!=null) {
// is killed
ReturnT<String> stopResult = new ReturnT<String>(ReturnT.FAIL_CODE, stopReason + " [job not executed, in the job queue, killed.]");
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(triggerParam.getLogId(), triggerParam.getLogDateTime(), stopResult));
}
}
// destroy
try {
handler.destroy();
} catch (Throwable e) {
logger.error(e.getMessage(), e);
}
logger.info(">>>>>>>>>>> xxl-job JobThread stoped, hashCode:{}", Thread.currentThread());
}

至此，整个XXlJOb的启动和接收请求的处理大致梳理完了。代码整体很简单。就不细致展开了。了解整个设计思想即可。

XXL-Job启动源码详解

1、xxl目录结构

1.1 xxl-job-admin

1.2 xxl-job-core

1.3 xxl-job-executor-samples

2、架构设计

2.1 整体架构设计

2.2 服务集成

3、启动源码分析

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XXL-Job启动源码详解

1、xxl目录结构

1.1 xxl-job-admin

1.2 xxl-job-core

1.3 xxl-job-executor-samples

2、架构设计

2.1 整体架构设计

2.2 服务集成

3、启动源码分析

热门文章

最新文章

相关电子书

相关实验场景