java – 进程无法访问该文件,因为它正被另一个进程使用

我有一段代码监视目录以添加文件.每当将新文件添加到目录时,将挑选该文件的内容并在kafka上发布,然后删除该文件.

这在我发出单个请求时有效,但是一旦我将代码从jMeter请求5或10个用户请求,内容就会在kafka上成功发布,但代码无法删除该文件.我收到一个FileSystemException,其中包含一个消息,该进程无法访问该文件,因为它正由另一个进程使用.

我想有一些我无法看到的并发问题.

public void monitor() throws IOException, InterruptedException {
    Path faxFolder = Paths.get(TEMP_FILE_LOCATION);
    WatchService watchService = FileSystems.getDefault().newWatchService();
    faxFolder.register(watchService, StandardWatchEventKinds.ENTRY_CREATE);
    boolean valid = true;
    do {
        WatchKey watchKey = watchService.take();
        for (WatchEvent<?> event : watchKey.pollEvents()) {
            if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
                String fileName = event.context().toString();
                publishToKafka(new File(TEMP_FILE_LOCATION + fileName).toPath(), "topic");
            }
        }
        valid = watchKey.reset();
    } while (valid);
}

private void publishToKafka(Path path, String topic) {
    try (BufferedReader reader = Files.newBufferedReader(path)) {
        String input = null;
        while ((input = reader.readLine()) != null) {
            kafkaProducer.publishMessageOnTopic(input, topic);
        }
    } catch (IOException e) {
        LOG.error("Could not read buffered file to send message on kafka.", e);
    } finally {
        try {
            Files.deleteIfExists(path); // This is where I get the exception
        } catch (IOException e) {
            LOG.error("Problem in deleting the buffered file {}.", path.getFileName(), e);
        }
    }
}

异常日志：

java.nio.file.FileSystemException: D:\upload\notif-1479974962595.csv: The process cannot access the file because it is being used by another process.

    at sun.nio.fs.WindowsException.translateToIOException(Unknown Source)
    at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
    at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
    at sun.nio.fs.WindowsFileSystemProvider.implDelete(Unknown Source)
    at sun.nio.fs.AbstractFileSystemProvider.deleteIfExists(Unknown Source)
    at java.nio.file.Files.deleteIfExists(Unknown Source)
    at com.panasonic.mdw.core.utils.MonitorDirectory$FileContentPublisher.publishToKafka(MonitorDirectory.java:193)
    at com.panasonic.mdw.core.utils.MonitorDirectory$FileContentPublisher.sendData(MonitorDirectory.java:125)
    at com.panasonic.mdw.core.utils.MonitorDirectory$FileContentPublisher.run(MonitorDirectory.java:113)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

解决方法:

看一下你的代码,似乎当一个文件被线程挑选再次发布时,另一个线程正在将其用于发布.这就是为什么没有人能够删除它.
它必须只是并发问题.您应该根据标准重新设计代码：可以同时运行的步骤和不可以运行的步骤.
因此整个过程中的步骤是：

>拿起一个文件(主线程应该这样做)
>发布文件(调用其他线程来做)
>删除文件(调用线程应删除它)
>检查是否存在任何文件(再次主线程可以执行)

此外,在选择文件的那一刻,您可以将其读入缓冲区,删除它然后继续发布.这将确保主线程不会将此文件分配给其他线程.

标签：java,file,java-8,java-nio-file
来源： https://codeday.me/bug/20190706/1393155.html