Vagrant，共享文件夹：利用inotify over NFS [英] Vagrant, shared folder: take advantage of inotify over NFS

问题描述

我们的Symfony2 webapp在开发模式中使用Assetic观察器来随时重新编译资产。

Our Symfony2 webapp uses the Assetic watcher in development mode to re-compile assets on the go.

webapp在一个运行在Vagrant VM中的Docker容器中运行（Ubuntu 12.04精确）。
主机是OSX 10.9小牛，它通过NFS（v3）共享与VM共享代码文件夹，代码通过Docker中的主机/客户机卷装载到容器中。

The webapp runs in a Docker container which runs in a Vagrant VM (Ubuntu 12.04 Precise). The host is OSX 10.9 Mavericks and it shares the code folder with the VM through a NFS (v3) share and the code is mounted in the container via a host/guest volume in Docker.

由于inotify似乎无法通过NFSv3检测文件修改，观察者工作在轮询模式，这可能非常慢（约1/2分钟来检测修改）。

Since inotify seems to not be able to detect file modifications over NFSv3, the watcher works in polling mode which can be very slow (~1/2 minutes to detect the modification).

我已经阅读了NFSv4是否符合标准，但我没有发现任何好的资源。

I've read that NFSv4 is inotify compliant but I did not found any good ressource on that.

有没有办法使NFS / inotify一起工作？

Is there a way to make NFS/inotify works together?

推荐答案

不幸的是，inotify 不能在NFS上工作。在内核中的VFS（虚拟文件系统）层中挂起自己的inotify工作。每当修改发生时，inotify都知道它，因为修改发生在同一台机器上，因此在同一个内核中 - 这使整个事情成为可能。

Unfortunately, inotify cannot work on NFS. inotify works by hooking itself in the VFS (virtual filesystem) layer, in the kernel. Whenever a modification happens, inotify knows about it, because the modification happens on the same machine, therefore in the same kernel — which makes the whole thing possible.

使用NFS，修改发生在服务器上，并且客户端需要通知。但是，在进行更改时，NFS不会通知客户端。否则，它不会扩展。 NFS已经被设计（和操作）在单个服务器上拥有数千个客户端。想象一下，如果你做了一个微小的变化，服务器必须推送给所有客户端！

With NFS, modifications happen on the server, and notifications are expected on the client. But the NFS doesn't notify the clients when a change is made. Otherwise, it wouldn't scale. NFS has been designed (and operated) to have thousands of clients on a single server. Imagine if you do a tiny change, and the server has to push it to all clients!

当然可以说嘿，应该有一个订阅机制NFS协议，以便客户端可以告诉服务器他们想知道特定位置发生的更改。那么，NFS是30年前设计的，所以原谅他们不包括这个订阅/通知系统： - ）

Of course, you could say "hey, there should be a subscription mechanism in the NFS protocol, so that clients can tell the server that they want to know about changes happening in a specific location". Well, NFS was designed 30 years ago, so forgive them for not including this subscription/notification system :-)

我不熟悉Assetic，但也许你可以有一个自定义脚本来手动监视更改，并在每次检测到更改时重新编译资源。只需浏览包含资源的目录，跟踪关联数组中每个文件的mtime，并且每次检测到新文件（或新的mtime）时，重新编译。 Boom！

I'm not familiar with Assetic, but maybe you could have a custom script to watch for changes manually, and re-compile assets each time you detect a change. Just walk through the directory containing the source for the assets, keep track of the mtime of each file in an associative array, and each time you detect a new file (or a new mtime), recompile. Boom!

另请参见关于inotify和NFS 。

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