title: Are multiple memory mapped files bugged?
body: <p>when adding a second memory mapped file to my project the first one no longer works cross processes.</p>
  <pre><code>Imports System.IO.MemoryMappedFiles
  
  Module IPC
      Private ReadOnly _QlCtxOpen As MemoryMappedViewAccessor = MemoryMappedFile.CreateOrOpen(&quot;IPC_QlCtxOpen&quot;, 1).CreateViewAccessor()
      Public Property IsQlCtxOpen As Boolean
           Get
              Dim value As Boolean = _QlCtxOpen.ReadBoolean(0)
              Debug.Print($&quot;QlCtxOpen {value}&quot;)
              Return value
          End Get
          Set(ByVal value As Boolean)
              _QlCtxOpen.Write(0, value)
              Debug.Print($&quot;set QlCtxOpen to {value}&quot;)
          End Set
      End Property
  End Module
  </code></pre>
  <p>when adding following line to the module the first mmf still works in the same process but a second process will no longer be able to read the correct value.</p>
  <pre><code>Private ReadOnly _alreadyOpenPID As MemoryMappedViewAccessor = MemoryMappedFile.CreateOrOpen(&quot;IPC_alreadyOpenPID&quot;, 4).CreateViewAccessor()
  </code></pre>
  <p>I know i should use a mutex for writing but in my project the write is triggered by mouse action so only 1 process will use it at the same time.</p>
  <p>I don't understand what i'm doing wrong to break the first mmf, it works w/o the second mmf.</p>
  <p>I'm using Microsoft Visual Studio Community 2019
  Version 16.11.11 .NET Framework 4.7.2</p>