从 java 轮询 NFS 共享会破坏文件系统

发布于 2024-10-21 20:47:00 字数 403 浏览 3 评论 0 原文

我们有两台服务器，每个服务器都有一个通过 NFS 映射的目录。

服务器 A 上的进程（shell 脚本）将文件放入映射驱动器中。

服务器 B 上的 Java 进程定期轮询映射驱动器并在找到文件后立即处理该文件。文件处理后 - 它被重命名（然后由服务器 A 上的 cron 进程删除）

该文件是一个小的 .properties 文件。几个周期后一切都运转良好。之后，服务器 A 和服务器 B 开始以不同的方式查看映射驱动器的内容。我们禁用了 NFS 缓存和属性查找。问题仍然存在。

如果我转到视图已损坏的服务器并执行以下操作：

ls

我将看到停滞的文件。但是，如果我再次执行此操作 - 将打印正确的文件列表。

我们将不胜感激任何有关此问题的帮助。

原文

We've got two servers having a directory mapped via NFS to each of them.

Process on server A (shell script) places file into mapped drive.

Java process on server B regularly polls mapped drive and processes the file as soon as it is found. After file is processed - it is renamed (and deleted by cron'ed process on server A afterwards)

The file is a small .properties file. Everything works well for couple of cycles. After that server A and server B start to see contents of mapped drive differently. We disabled NFS caching and attribute lookup. Problem is still there.

If I go to a server which has broken view and do:

ls

I'll see stalled files. BUT, if I do it again - correct file listing is printed.

We'd appreciate any help on the issue.

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漫雪独思 2024-10-28 20:47:00

我的问题是，当使用计时器循环时，下面的命令会停止看到实际的目录内容。它与 NFS 服务器不同步。

File[] files = dir.listFiles(new MyFileFilter() );

我得到的解决方案是请求已知不存在的文件。我认为这会使 NFS 客户端修复或刷新其状态。

// Key point is here: we ask NFS client to obtain unexisting file. Since the client
// cannot find it locally - it will make a call to the NFS server which will 
// fix client cache or whatever it uses locally when cache is disabled.
File temp = new File(dir, "unexisting.file");
temp.exists();

如果您知道此解决方法背后的机制 - 请分享！

My problem was that when looping with timer, command below stops seeng actual directory content. It gets out of sync with NFS server.

File[] files = dir.listFiles(new MyFileFilter() );

The solution I've got is to request knowingly unexisting file. I assume that this makes NFS client to fix or refresh its state.

// Key point is here: we ask NFS client to obtain unexisting file. Since the client
// cannot find it locally - it will make a call to the NFS server which will 
// fix client cache or whatever it uses locally when cache is disabled.
File temp = new File(dir, "unexisting.file");
temp.exists();

If you know the mechanism behind this workaround - please share!

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