A thread acquiring a lock on an object that can be accessed across application domain boundaries runs the risk of being blocked by another thread in a different application domain. Objects that can be accessed across application domain boundaries are said to have weak identity. Types with weak identity are:

• MarshalByRefObject
• ExecutionEngineException
• OutOfMemoryException
• StackOverflowException
• String
• MemberInfo
• ParameterInfo
• Thread

Noncompliant Code Example

Public Class Sample

    Private myString As String = "foo"

    Public Sub Go()
        SyncLock myString   ' Noncompliant
        End SyncLock
    End Sub

End Class

Compliant Solution

Public Class Sample

    Private Shared ReadOnly fLock As New Object

    Public Sub Go()
        SyncLock fLock
        End SyncLock
    End Sub

End Class