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本文主要讲一下jesque的WorkerImpl与WorkerPool。
resque
Resque是一个使用redis来创建后台任务的ruby组件。而jesque是其java版本。通常用来做延时队列。
WorkerImpl
List<String> queues = Arrays.asList(delayedQueue);
final Worker worker = new WorkerImpl(jesqueConfig,queues, new MapBasedJobFactory(map(entry("DemoJob", DemoJob.class))));
final Thread workerThread = new Thread(worker);
workerThread.start();
这是worker实例
jesque-2.1.2-sources.jar!/net/greghaines/jesque/worker/WorkerImpl.java
/**
* Starts this worker. Registers the worker in Redis and begins polling the queues for jobs.<br>
* Stop this worker by calling end() on any thread.
*/
@Override
public void run() {
if (this.state.compareAndSet(NEW, RUNNING)) {
try {
renameThread("RUNNING");
this.threadRef.set(Thread.currentThread());
this.jedis.sadd(key(WORKERS), this.name);
this.jedis.set(key(WORKER, this.name, STARTED), new SimpleDateFormat(DATE_FORMAT).format(new Date()));
this.listenerDelegate.fireEvent(WORKER_START, this, null, null, null, null, null);
this.popScriptHash.set(this.jedis.scriptLoad(ScriptUtils.readScript(POP_LUA)));
this.lpoplpushScriptHash.set(this.jedis.scriptLoad(ScriptUtils.readScript(LPOPLPUSH_LUA)));
this.multiPriorityQueuesScriptHash
.set(this.jedis.scriptLoad(ScriptUtils.readScript(POP_FROM_MULTIPLE_PRIO_QUEUES)));
poll();
} catch (Exception ex) {
LOG.error("Uncaught exception in worker run-loop!", ex);
this.listenerDelegate.fireEvent(WORKER_ERROR, this, null, null, null, null, ex);
} finally {
renameThread("STOPPING");
this.listenerDelegate.fireEvent(WORKER_STOP, this, null, null, null, null, null);
this.jedis.srem(key(WORKERS), this.name);
this.jedis.del(key(WORKER, this.name), key(WORKER, this.name, STARTED), key(STAT, FAILED, this.name),
key(STAT, PROCESSED, this.name));
this.jedis.quit();
this.threadRef.set(null);
}
} else if (RUNNING.equals(this.state.get())) {
throw new IllegalStateException("This WorkerImpl is already running");
} else {
throw new IllegalStateException("This WorkerImpl is shutdown");
}
}
实现了runnable方法，里头poll方法无限循环
/**
* Polls the queues for jobs and executes them.
*/
protected void poll() {
int missCount = 0;
String curQueue = null;
while (RUNNING.equals(this.state.get())) {
try {
if (threadNameChangingEnabled) {
renameThread("Waiting for " + JesqueUtils.join(",", this.queueNames));
}
curQueue = getNextQueue();
if (curQueue != null) {
checkPaused();
// Might have been waiting in poll()/checkPaused() for a while
if (RUNNING.equals(this.state.get())) {
this.listenerDelegate.fireEvent(WORKER_POLL, this, curQueue, null, null, null, null);
final String payload = pop(curQueue);
if (payload != null) {
process(ObjectMapperFactory.get().readValue(payload, Job.class), curQueue);
missCount = 0;
} else {
missCount++;
if (shouldSleep(missCount) && RUNNING.equals(this.state.get())) {
// Keeps worker from busy-spinning on empty queues
missCount = 0;
Thread.sleep(EMPTY_QUEUE_SLEEP_TIME);
}
}
}
}
} catch (InterruptedException ie) {
if (!isShutdown()) {
recoverFromException(curQueue, ie);
}
} catch (JsonParseException | JsonMappingException e) {
// If the job JSON is not deserializable, we never want to submit it again...
removeInFlight(curQueue);
recoverFromException(curQueue, e);
} catch (Exception e) {
recoverFromException(curQueue, e);
}
}
}
不断地pop和process
/**
* Materializes and executes the given job.
*
* @param job the Job to process
* @param curQueue the queue the payload came from
*/
protected void process(final Job job, final String curQueue) {
try {
this.processingJob.set(true);
if (threadNameChangingEnabled) {
renameThread("Processing " + curQueue + " since " + System.currentTimeMillis());
}
this.listenerDelegate.fireEvent(JOB_PROCESS, this, curQueue, job, null, null, null);
this.jedis.set(key(WORKER, this.name), statusMsg(curQueue, job));
final Object instance = this.jobFactory.materializeJob(job);
final Object result = execute(job, curQueue, instance);
success(job, instance, result, curQueue);
} catch (Throwable thrwbl) {
failure(thrwbl, job, curQueue);
} finally {
removeInFlight(curQueue);
this.jedis.del(key(WORKER, this.name));
this.processingJob.set(false);
}
}
而process这个方法，就是实例化目标job，然后execute
/**
* Executes the given job.
*
* @param job the job to execute
* @param curQueue the queue the job came from
* @param instance the materialized job
* @throws Exception if the instance is a {@link Callable} and throws an exception
* @return result of the execution
*/
protected Object execute(final Job job, final String curQueue, final Object instance) throws Exception {
if (instance instanceof WorkerAware) {
((WorkerAware) instance).setWorker(this);
}
this.listenerDelegate.fireEvent(JOB_EXECUTE, this, curQueue, job, instance, null, null);
final Object result;
if (instance instanceof Callable) {
result = ((Callable<?>) instance).call(); // The job is executing!
} else if (instance instanceof Runnable) {
((Runnable) instance).run(); // The job is executing!
result = null;
} else { // Should never happen since we're testing the class earlier
throw new ClassCastException(
"Instance must be a Runnable or a Callable: " + instance.getClass().getName() + " - " + instance);
}
return result;
}
而execute就是调用call或者run方法。
从这里可以看出是单线程阻塞的，如果一个job比较耗时，是会影响其他job的触发和执行。
WorkerPool
jesque-2.1.2-sources.jar!/net/greghaines/jesque/worker/WorkerPool.java
/**
* Create a WorkerPool with the given number of Workers and the given <code>ThreadFactory</code>.
* @param workerFactory a Callable that returns an implementation of Worker
* @param numWorkers the number of Workers to create
* @param threadFactory the factory to create pre-configured Threads
*/
public WorkerPool(final Callable<? extends Worker> workerFactory, final int numWorkers,
final ThreadFactory threadFactory) {
this.workers = new ArrayList<>(numWorkers);
this.threads = new ArrayList<>(numWorkers);
this.eventEmitter = new WorkerPoolEventEmitter(this.workers);
for (int i = 0; i < numWorkers; i++) {
try {
final Worker worker = workerFactory.call();
this.workers.add(worker);
this.threads.add(threadFactory.newThread(worker));
} catch (RuntimeException re) {
throw re;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
/**
* {@inheritDoc}
*/
@Override
public void run() {
for (final Thread thread : this.threads) {
thread.start();
}
Thread.yield();
}
/**
* {@inheritDoc}
*/
@Override
public void end(final boolean now) {
for (final Worker worker : this.workers) {
worker.end(now);
}
}
workerpool维护了一组worker实例，起线程池的作用，尽可能提高job的并发度。
