Mac主机Docker映射卷中.Net Core创建FileStream遇FileNotFoundException

环境背景 #

• 应用运行在Linux Docker容器中，宿主系统为MacOS，处于调试模式
• Docker Compose卷映射配置：

volumes:
      - /Users/blabla/Temp:/temp

异常现象 #

调用File.OpenRead时偶尔抛出System.IO.FileNotFoundException，堆栈信息如下：

at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirectory, Func`2 errorRewriter)
   at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String path, OpenFlags flags, Int32 mode)
   at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize)
   at System.IO.Strategies.OSFileStreamStrategy..ctor(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize)
   at System.IO.Strategies.FileStreamHelpers.ChooseStrategy(FileStream fileStream, String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, Int64 preallocationSize)
   at System.IO.FileStream..ctor(String path, FileMode mode)

测试场景对比 #

场景1：使用Mac宿主映射卷中的文件 #

测试代码：

var mappedFolderPath = "/temp/testFile.png";
var exist = System.IO.File.Exists(mappedFolderPath);

for (int i = 0; i < 1000; i++)
{
    try
    {
        using var streamForTest = System.IO.File.OpenRead(mappedFolderPath);
        var justForTest = streamForTest.Length;
    }
    catch (Exception ex)
    {
        // 3-4次循环后触发异常
        var exception = ex;
    }
}

现象：File.Exists返回true，但循环几次后抛出上述异常。

场景2：使用容器内输出目录的文件 #

通过.csproj配置将文件复制到容器内输出目录：

...
 <ItemGroup>
    <None Update="StaticContent\testFile.png">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>
...

测试代码：

var root = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
var path = Path.Combine(root, "StaticContent", "testFile.png");
var exist = System.IO.File.Exists(path);

for (int i = 0; i < 1000; i++)
{
    try
    {
        using var streamForTest = System.IO.File.OpenRead(path);
        var justForTest = streamForTest.Length;
    }
    catch (Exception ex)
    {
        // 从未触发异常
        var exception = ex;
    }
}

现象：File.Exists返回true，循环全程无异常。

核心疑问 #

两种场景下File.Exists均返回true，为何映射卷场景会偶尔抛出文件不存在的异常？

内容的提问来源于stack exchange，提问作者Artem