NotifyFilters.LastWrite ...

Question

In Mono's Technical FAQ, you can find a

What are the issues with FileSystemWatcher?

FileSystemWatcher watcher = new FileSystemWatcher(directory);
watcher.NotifyFilter = NotifyFilters.LastAccess;
watcher.Changed += OnChanged;
watcher.IncludeSubdirectories = includeSubdirectories;
watcher.EnableRaisingEvents = true;

section, which says that under certain conditions

• Mono falls back to polling the directories for changes, which far from optimal.

Experimentally, I found out that one of these conditions is:

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The total number of watched directories is more than 4096WatcherChangeTypes.ChangedThere may be more conditions related to files count, but I did not met them.

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So, you may face the described problem if the following conditions are met:You run a .NET Framework 4.7 code under Mono 6.8 on Linux (or in Docker)

You use

Answer 1

Your NotifyFilter includes

NotifyFilters

.LastAccess

The

command returns more than 4096 在Linux上的沉重CPU负荷

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我订阅了一个目录内的变化。

1. 大多数时候，这段.NET 4.7的代码都能正常工作，但是当它在Debian的Mono下运行时，在某些目录下，我注意到了以下行为。
2. CPU负载增加到250%(2.5个核心完全加载)子线程的数量增加，它们会给CPU带来负载这样无休止地持续下去，直到应用程序完全卡住。
3. UPD：另外的研究表明，CPU的重度负载是由无休止的洪流引起的。 监视目录内的每一个子目录的事件（每一个目录连续发生1-2个事件，当所有的目录都被报告为被改变时，它又开始了）。UPD: 最小的错误例子
4. find watched-directory -type d | wc -l我订阅一个目录里面的变化。FileSystemWatcher watcher = new FileSystemWatcher(directory); watcher.NotifyFilter = NotifyFilters.LastAccess.