[英]Thread.start() throwing exception after Thread.isAlive() check
[英]Do I need to check for Thread.isAlive() here?
在Web控制器中,我有一個接收請求的父線程。 有些請求需要很長時間才能處理。 為了防止客戶端超時,我設置父線程每2秒發送一個字節,而子線程正在執行耗時的操作部分。
我想確保我考慮到子線程死亡的所有可能情況,但我也不想進行任何無關的檢查。
這是父線程:
// This is my runnable class
ProcessorRunnable runnable = new ProcessorRunnable(settings, Thread.currentThread());
Thread childThread = new Thread(runnable);
childThread.start();
boolean interrupted = false;
while (!runnable.done) { // <-- Check in question
outputStream.write(' ');
outputStream.flush();
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// If the runnable is done, then this was an expected interrupt
// Otherwise, remember the interruption and re-interrupt after processing is done
// Or with self so that a later expected interrupt won't clear out an earlier unexpected one
interrupted = interrupted || !runnable.done;
}
}
if (runnable.runtimeException != null) {
LOG.error("Propagating runtime exception from thread");
throw runnable.runtimeException;
}
// ... Further processing on the results provided by the child thread
這里是ProcessorRunnable:
private volatile boolean done;
private volatile Result result;
private volatile RuntimeException runtimeException;
// ...
public void run() {
done = false;
try {
result = myService.timeConsumingOperation(settings);
} catch (RuntimeException e) {
runtimeException = e;
} finally {
done = true;
parentThread.interrupt();
}
}
我的問題是,在父線程的主循環中添加&& Thread.isAlive()
檢查會給我帶來什么嗎? 似乎在finally
塊中設置done = true
應該可以解決問題,但是在某些情況下,這個子線程可能會死而不通知父級嗎?
子線程中的finally
將始終在完成之前執行。 即使該線程被中斷或停止,這也會發生異常,它會使調用堆棧冒泡並finally
觸發所有s。 因此,如果子線程被中斷,則done
將始終為true。
對於像這樣的后台任務,您可能希望使用ExecutorService
而不是原始線程。 您可以向ExecutorService
提交Runnable
,並在返回的future上調用get()
直到它完成為止。 如果要在等待時打印出空格,可以使用循環,以超時方式調用get()
版本。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.