????????????
????LinkedBlockingQueue ????? Executors ???е???????? ThreadPoolExecutor ?????????????У?PriorityBlockingQueue ???????????BlockingQueue?????????????趨?????????????????????????????????????????? Runnable ?? Callable ?????????????????? RunnableFuture??????????????У?ProrityBlockingQueue ??????????????????е?????????????????????RunnableFuture???????????????????????????? corePoolSize ????1????????????????ThreadPoolExecutor ??????????????????У??????? PriorityBlockingQueue ????????????????
???????????￡?ThreadPoolExecutor ????????У?workQueue??????б??????????????????????????????б?????????п????????ó???????????out of memory????????????????????е??С?????????? RejectionExecutionHandler???????????崦?????????4?????д??????????AbortPolicy????????????
????CallerRunsPolicy
????AbortPolicy
????DiscardPolicy
????DiscardOldestPolicy
??????????
?????????????????????????????????磬??????????????? Thread.UncaughtExceptionHandler ????????????????????????????У????????????????????????δ?????????
????public class LoggingThreadFactory implements ThreadFactory {
????private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
????private static final String THREAD_NAME_PREFIX = "worker-thread-";
????private final AtomicInteger threadCreationCounter = new AtomicInteger();
????@Override
????public Thread newThread(Runnable task) {
????int threadNumber = threadCreationCounter.incrementAndGet();
????Thread workerThread = new Thread(task?? THREAD_NAME_PREFIX + threadNumber);
????workerThread.setUncaughtExceptionHandler(thread?? throwable -> logger.error("Thread {} {}"?? thread.getName()?? throwable));
????return workerThread;
????}
????}
???????????????????
???????????????????????????????????????????????????У???????? ExecutorService ??????????????????????????????????????????????????????????????е??????????????????????о???????????????
????Producer ??????????????μ??????????????????????????? ExecutorService??ExecutorService ??????????е????????????????? Consumer???????????????????????????????????
???????????????? Spring ???????
????@Configuration
????public class ProducerConsumerConfiguration {
????<a href='http://www.jobbole.com/members/weibo_1902876561'>@Bean</a>
????public ExecutorService executorService() {
????// single consumer
????return Executors.newSingleThreadExecutor();
????}
????// other beans such as a data source?? a scheduler?? etc.
????}
?????????????? Consumer ????? ConsumerFactory???ù?????????????????????????????????δ????????????????????????????и?????
public class Consumer implements Runnable {
private final BusinessTask businessTask;
private final BusinessLogic businessLogic;
public Consumer(BusinessTask businessTask?? BusinessLogic businessLogic) {
this.businessTask = businessTask;
this.businessLogic = businessLogic;
}
@Override
public void run() {
businessLogic.processTask(businessTask);
}
}
@Component
public class ConsumerFactory {
private final BusinessLogic businessLogic;
public ConsumerFactory(BusinessLogic businessLogic) {
this.businessLogic = businessLogic;
}
public Consumer newConsumer(BusinessTask businessTask) {
return new Consumer(businessTask?? businessLogic);
}
}
??????????? Producer ?????????????л????????????????????????????У??????? fetchData() ????? scheduler ???????????
@Component
public class Producer {
private final DataRepository dataRepository;
private final ExecutorService executorService;
private final ConsumerFactory consumerFactory;
@Autowired
public Producer(DataRepository dataRepository?? ExecutorService executorService??
ConsumerFactory consumerFactory) {
this.dataRepository = dataRepository;
this.executorService = executorService;
this.consumerFactory = consumerFactory;
}
public void fetchAndSubmitForProcessing() {
List<Data> data = dataRepository.fetchNew();
data.stream()
// create a business task from data fetched from the database
.map(BusinessTask::fromData)
// create a consumer for each business task
.map(consumerFactory::newConsumer)
// submit the task for further processing in the future (submit is a non-blocking method)
.forEach(executorService::submit);
}
}
?????????л ExecutorService???????????????о?????????????????????????????????????????????????????????????????????????????????????????????????????????????
???????
????JDK 5 ??????2004????????????????????ExecutorService ???????е????????????????????????????? Tomcat ?? Undertow????????????????????????????????????????κ???????У?embarrassingly parallel???????????????????á???????????????????????????????????????ù?????