Java多線程問題

在下面的代碼中，我的主要任務是不等待子任務完成其執行。我是Java Thread的新手。所以我無法修復它。我谷歌，發現沒有運氣。請幫我解決這個線程問題。代碼：Java多線程問題

class ExecutorServiceManager{ 
public static ExecutorService getExecutor() { 
    if (executorService == null) { 
     try { 
      lock.lock(); 
      if (executorService == null) { 
       executorService = Executors.newFixedThreadPool(150); 
      } 
     } finally { 
      lock.unlock(); 
     } 
    } 

    if(executorService instanceof ThreadPoolExecutor) { 
     ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService; 
     int corePoolSize = threadPoolExecutor.getCorePoolSize(); 
     int maximumPoolSize = threadPoolExecutor.getMaximumPoolSize(); 
     Logger.info(ExecutorServiceManager.class, "ExecutorInfo: CorePoolSize:%s, MaxPoolSize:%s", corePoolSize, maximumPoolSize); 
    } 
    return executorService; 
}} 

class ServiceImpl{ 
ExecutorServiceManager executorServiceManager; 
private void processConversion(String category, Map<String, String> couchDeltaMap, String processKey, String reqId) { 
    try { 
     ProgressVo progressVo = new ProgressVo(); 
     CountDownLatch pgCntxtcountDownLatch = new CountDownLatch(1); 
     executorServiceManager.getExecutor().submit(new MainTask(category, processKey, pgCntxtcountDownLatch, executorServiceManager, progressVo)); 
     Logger.info(ServiceImpl.class, "ExecutorInfo: CorePoolSize:%s, MaxPoolSize:%s", corePoolSize, maximumPoolSize); 
     pgCntxtcountDownLatch.await(); 
    } catch(InterruptedException ie) {} 
     catch(Exception ex) {} 
}} 

class MainTask implements Runnable{ 
@Override 
public void run() {  
    executorService = executorServiceManager.getExecutor(); 
    executorService.submit(new SubTask(progressVo, couchDeltaMap, reqId, executorServiceManager)); 

    //I want the below operation to be executed, if and only the subtask completed its execution. 
    //But the below logger is printing before the subtask completed its execution.  
    Logger.info(MainTask.class, "It got executed before the subtask completed its processing"); 
    pgCntxtcountDownLatch.countDown(); 
}} 

class SubTask implements Runnable{ 
@Override 
public void run() {  
    executorService = executorServiceManager.getExecutor(); 
    doSomeProcess; 
    //It stopped in the middle, and the Main task started executing the remaining operation 
}}

來源

2017-03-03 Ismail

雙檢鎖壞了，除非你採取某些步驟，這是不必要的，因爲不管怎樣都不應該使用雙重檢查鎖定。你有沒有采取措施確保不必要的雙重檢查鎖定習慣用法能正常工作？ –

如果你是java線程的新手，我會堅持使用基本的線程類。它會迫使你理解機制，然後你可以使用更容易使用的類，如果理解機制 – efekctive

爲了讓你的主要任務等待子任務的執行，你可以使用由Executor.submit()返回Future這樣：

class MainTask implements Runnable{ 
@Override 
public void run() {  
    executorService = executorServiceManager.getExecutor(); 
    Future subTask = executorService.submit(new SubTask(progressVo, couchDeltaMap, reqId, executorServiceManager)); 
    try{ 
     subTask.get(); //wait for completion of the subtask 
    } catch(Exception e){ 
     //You probably want better exception catching, this is just an example 
    } 

    Logger.info(MainTask.class, "It got executed before the subtask completed its processing"); 
    pgCntxtcountDownLatch.countDown(); 
}}

來源

2017-03-04 00:16:53 Adonis

感謝您的代碼。我試着像你所說的那樣。請參閱下面的代碼。即使使用此代碼，我在控制檯中也看不到記錄器「內部線程正在運行結束」消息。 – Ismail

我無法在此評論框中添加代碼。因此我把它放在答案部分。請參閱該代碼。即使使用此代碼，我在控制檯中也看不到記錄器「內部線程正在運行結束」消息。而我正在看MainTask記錄器，並說它已完成處理。 – Ismail

class MainTask implements Runnable{ 
@Override 
public void run() { 
executorService = manager.getExecutor(); 
List<Future<Runnable>> futures = new ArrayList<Future<Runnable>>(); 
while (!pageCntxts.isEmpty()) { 
    popped = pageCntxts.pop(); 
    Future future = executorService.submit(new SubTask(progressVo, couchDeltaMap, reqId,manager)); 
    futures.add(future); 
    if(pageCntxts.isEmpty()) 
     loadPageCntxtWithNext25Records(progressVo); 
    processNum++; 
} 
Logger.debug(MainTask.class, "Internal Thread Running Starts with data size: "+futures.size()); 
for (Future<Runnable> future : futures) { 
    future.get(); 
} 
Logger.debug(MainTask.class, "Internal Thread Running Ends");}}

來源

2017-03-04 17:59:48 Ismail

Java多線程問題

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