如何关闭并行流中使用的本地autocloseable线程？

Question

我有一个ThreadLocal变量.我想像这样使用它:

ThreadLocal<AutoCloseable> threadLocal = new ThreadLocal<AutoCloseable>(); // pseudocode
ForkJoinPool fj = new ForkJoinPool(nThreads);
fj.submit(
    () -> myStream.parallel().forEach(e -> {
        /*I want to use the thread local autocloseable here, 
          but how do I close it when this parallel processing is done?*/
    })
);

Answer 1

ThreadLocal在使用它们的线程死后关闭.如果你想控制它,你需要使用地图.

// do our own thread local resources which close when we want.
Map<Thread, Resource> threadLocalMap = new ConcurrentHashMap<>();

fj.submit(
() -> myStream.parallel().forEach(e -> {
     Resource r = threadLocalMap.computeIfAbsent(Thread.currentThread(), t -> new Resource();
    // use the thread local autocloseable here, 
})

// later once all the tasks have finished.
// close all the thread local resources when the parallel processing is done
threadLocalMap.values().forEach(Utils::closeQuietly);

有一种方法可以在不抛出异常的情况下关闭资源.Chronicle有一个,但许多其他库也是如此.

public static void closeQuietly(Closeable c) {
    if (c != null) {
       try {
           c.close();
       } catch (IOException ioe) {
           // ignore or trace log it
       }
    }
}

很可能你有一个方法在你的项目中做到这一点 https://www.google.co.uk/search?q=public+static+void+closequietly+Closeable