在xxl-job客户端的启动流程中，有一个步骤是“初始化任务执行器内置服务”，其实就是监听端口并接收来自xxl-job服务端的请求，其中就包括任务调度的请求。
处理任务调度请求的逻辑由ExecutorBiz接口的run()负责，ExecutorBiz的实现类是ExecutorBizImpl，所以直接看ExecutorBizImpl对run方法的实现
@Override
public ReturnT<String> run(TriggerParam triggerParam) {
// load old：jobHandler + jobThread
JobThread jobThread = XxlJobExecutor.loadJobThread(triggerParam.getJobId());
IJobHandler jobHandler = jobThread!=null?jobThread.getHandler():null;
String removeOldReason = null;
// valid：jobHandler + jobThread
GlueTypeEnum glueTypeEnum = GlueTypeEnum.match(triggerParam.getGlueType());
if (GlueTypeEnum.BEAN == glueTypeEnum) {
// new jobhandler
IJobHandler newJobHandler = XxlJobExecutor.loadJobHandler(triggerParam.getExecutorHandler());
// valid old jobThread
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;
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;
}
// valid handler
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
}
}
// replace thread (new or exists invalid)
if (jobThread == null) {
jobThread = XxlJobExecutor.registJobThread(triggerParam.getJobId(), jobHandler, removeOldReason);
}
// push data to queue
ReturnT<String> pushResult = jobThread.pushTriggerQueue(triggerParam);
return pushResult;
}
总的来说，任务处理器的执行过程主要包含3个步骤：
- 任务执行线程的创建
- 调度请求的入队
- 任务处理器的执行
任务执行线程的创建
ExecutorBizImpl的run方法中，任务执行线程的创建逻辑：- 通过XxlJobExecutor.loadJobThread(triggerParam.getJobId())加载任务id对应的任务执行线程（JobThread对象），再从JobThread对象中加载老的任务执行器IJobHandler对象。
- 根据调度请求中不同的任务类型，判断老任务处理器是否可用，若不可用则加载新任务处理器。
- 如果老任务处理器不可用了，则通过XxlJobExecutor.registJobThread(triggerParam.getJobId(), jobHandler, removeOldReason)，将任务id、任务处理器、移除理由这3个对象封装成新的JobThread对象。以任务id为key，新的JobThread对象为value，存入全局的ConcurrentMap<Integer, JobThread> jobThreadRepository。
调度请求的入队
通过调用jobThread.pushTriggerQueue(triggerParam)，将triggerParam添加到该任务执行线程内的阻塞队列triggerQueue中，如果重复调度则返回调度失败；添加成功则返回调度成功。至此，对xxl-job服务端的调度请求就处理完成了，至于任务处理器的执行，实际是在JobThread线程中异步进行的。 /**
* new trigger to queue
*
* @param triggerParam
* @return
*/
public ReturnT<String> pushTriggerQueue(TriggerParam triggerParam) {
// avoid repeat
if (triggerLogIdSet.contains(triggerParam.getLogId())) {
logger.info(">>>>>>>>>>> repeate trigger job, logId:{}", triggerParam.getLogId());
return new ReturnT<String>(ReturnT.FAIL_CODE, "repeate trigger job, logId:" + triggerParam.getLogId());
}
triggerLogIdSet.add(triggerParam.getLogId());
triggerQueue.add(triggerParam);
return ReturnT.SUCCESS;
}
任务处理器的执行
任务处理器的执行逻辑放在JobThread的run()中： @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;
try {
// to check toStop signal, we need cycle, so wo cannot use queue.take(), instand of poll(timeout)
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 xxlJobContext = new XxlJobContext(
triggerParam.getJobId(),
triggerParam.getExecutorParams(),
logFileName,
triggerParam.getBroadcastIndex(),
triggerParam.getBroadcastTotal());
// init job context
XxlJobContext.setXxlJobContext(xxlJobContext);
// execute
XxlJobHelper.log("<br>----------- xxl-job job execute start -----------<br>----------- Param:" + xxlJobContext.getJobParam());
if (triggerParam.getExecutorTimeout() > 0) {
// limit timeout
Thread futureThread = null;
try {
FutureTask<Boolean> futureTask = new FutureTask<Boolean>(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
// init job context
XxlJobContext.setXxlJobContext(xxlJobContext);
handler.execute();
return true;
}
});
futureThread = new Thread(futureTask);
futureThread.start();
Boolean tempResult = futureTask.get(triggerParam.getExecutorTimeout(), TimeUnit.SECONDS);
} catch (TimeoutException e) {
XxlJobHelper.log("<br>----------- xxl-job job execute timeout");
XxlJobHelper.log(e);
// handle result
XxlJobHelper.handleTimeout("job execute timeout ");
} finally {
futureThread.interrupt();
}
} else {
// just execute
handler.execute();
}
// valid execute handle data
if (XxlJobContext.getXxlJobContext().getHandleCode() <= 0) {
XxlJobHelper.handleFail("job handle result lost.");
} else {
String tempHandleMsg = XxlJobContext.getXxlJobContext().getHandleMsg();
tempHandleMsg = (tempHandleMsg!=null&&tempHandleMsg.length()>50000)
?tempHandleMsg.substring(0, 50000).concat("...")
:tempHandleMsg;
XxlJobContext.getXxlJobContext().setHandleMsg(tempHandleMsg);
}
XxlJobHelper.log("<br>----------- xxl-job job execute end(finish) -----------<br>----------- Result: handleCode="
+ XxlJobContext.getXxlJobContext().getHandleCode()
+ ", handleMsg = "
+ XxlJobContext.getXxlJobContext().getHandleMsg()
);
} 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) {
XxlJobHelper.log("<br>----------- JobThread toStop, stopReason:" + stopReason);
}
// handle result
StringWriter stringWriter = new StringWriter();
e.printStackTrace(new PrintWriter(stringWriter));
String errorMsg = stringWriter.toString();
XxlJobHelper.handleFail(errorMsg);
XxlJobHelper.log("<br>----------- JobThread Exception:" + errorMsg + "<br>----------- xxl-job job execute end(error) -----------");
} finally {
if(triggerParam != null) {
// callback handler info
if (!toStop) {
// commonm
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(
triggerParam.getLogId(),
triggerParam.getLogDateTime(),
XxlJobContext.getXxlJobContext().getHandleCode(),
XxlJobContext.getXxlJobContext().getHandleMsg() )
);
} else {
// is killed
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(
triggerParam.getLogId(),
triggerParam.getLogDateTime(),
XxlJobContext.HANDLE_CODE_FAIL,
stopReason + " [job running, killed]" )
);
}
}
}
}
// callback trigger request in queue
while(triggerQueue !=null && triggerQueue.size()>0){
TriggerParam triggerParam = triggerQueue.poll();
if (triggerParam!=null) {
// is killed
TriggerCallbackThread.pushCallBack(new HandleCallbackParam(
triggerParam.getLogId(),
triggerParam.getLogDateTime(),
XxlJobContext.HANDLE_CODE_FAIL,
stopReason + " [job not executed, in the job queue, killed.]")
);
}
}
// destroy
try {
handler.destroy();
} catch (Throwable e) {
logger.error(e.getMessage(), e);
}
logger.info(">>>>>>>>>>> xxl-job JobThread stoped, hashCode:{}", Thread.currentThread());
}
核心逻辑是：
- 通过while(!toStop)不停从triggerQueue中拉取调度参数，拉取设置了3秒的超时时间。
- 拉取失败，空闲次数+1。如果空闲次数超过30次，则将当前这个JobThread对象从jobThreadRepository删除。
- 拉取成功，空闲次数置为0，然后判断任务执行是否设置了超时时间，
- 设置了超时时间，将任务执行器封装成FutureTask对象，创建一个新的线程去执行，通过FutureTask对象的get方法判断执行是否超市。
- 没设置超时时间，用当前的线程（JobThread对象）执行任务执行器的execute方法。
- 从while(!toStop)跳出，说明JobThread线程的toStop参数被置为true，或者JobThread的空闲次数>30次，不管哪种情况，都需要再从triggerQueue尝试拉取调度参数，把未执行的调度参数封装成调度结果，通过TriggerCallbackThread.pushCallBack方法异步同步到xxl-job服务端。
