Java executorsevice正在關閉，即使它的線程正在運行

Question

我正在使用Executorsevice從數據庫生成文件。我正在使用jdbc和核心java將表格數據存入文件。

使用10個線程創建Executorservice後，我在for循環中提交60個線程以並行獲取60個文件。這對小數據和少數列的表格工作正常。但是，如果文件很大，並且對於具有更多列的表，正在處理巨大表數據/更多列表的線程正在停止，而在其他線程完成時不會在日誌中提供任何信息。

ExecutorService executor = Executors.newFixedThreadPool(THREAD_COUNT); 
     for (String filename : filenames) { 
      EachFileThread worker = new EachFileThread(destdir, converter, 
        filename, this); 
      executor.execute(worker); 
     } 
     executor.shutdown(); 

裏面Eachfilethread我讀取XML並獲得列，表，形成一個查詢，執行查詢和格式化的數據，並把數據轉換成文件

forTable = (FileData) converter.convertFromXMLToObject(filename + ".xml"); 
    String query = getQuery(forTable); 
    statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY); 
    resultSet = statement.executeQuery(query); 
resultSet.setFetchSize(3000); 
    WriteData(resultSet, filepath, forTable);(formatting the data from db and then writing to a file) 

Answer 1

的問題是，你是不等待所有的工作完成他們正在做的事情。作爲@msandiford在評論所說，你應該調用shutdown()後添加調用awaitTermination(..)因爲它是在樣品shutdownAndAwaitTermination()方法上https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ExecutorService.html

例如，你可以嘗試做它像這樣：

ExecutorService executor = Executors.newFixedThreadPool(THREAD_COUNT); 
for (String filename : filenames) { 
    EachFileThread worker = new EachFileThread(destdir, converter, filename, this); 
    executor.execute(worker); 
} 
executor.shutdown(); 
try { 
    // Wait a while for existing tasks to terminate 
    if (!executor.awaitTermination(60, TimeUnit.SECONDS)) { 
     executor.shutdownNow(); // Cancel currently executing tasks 
     // Wait a while for tasks to respond to being cancelled 
     if (!executor.awaitTermination(60, TimeUnit.SECONDS)) 
      System.err.println("Executor did not terminate"); 
    } 
} catch (InterruptedException ie) { 
    // (Re-)Cancel if current thread also interrupted 
    executor.shutdownNow(); 
    // Preserve interrupt status 
    Thread.currentThread().interrupt(); 
}