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Do not lock on objects with weak identity







Breaking Change

Non Breaking

A thread attempts to acquire a lock on an object that has a weak identity.

An object is said to have a weak identity when it can be directly accessed across application domain boundaries. A thread that tries to acquire a lock on an object that has a weak identity can be blocked by a second thread in a different application domain that has a lock on the same object. The following types have a weak identity and are flagged by the rule:

To fix a violation of this rule, use an object from a type that is not in the list in the Description section.

Do not suppress a warning from this rule.

The following example shows some object locks that violate the rule.

Imports System
Imports System.IO
Imports System.Reflection
Imports System.Threading

Namespace ReliabilityLibrary

   Class WeakIdentities

      Sub SyncLockOnWeakId1()

         SyncLock GetType(WeakIdentities)
         End SyncLock 

      End Sub 

      Sub SyncLockOnWeakId2() 

         Dim stream As New MemoryStream()
         SyncLock stream
         End SyncLock 

      End Sub 

      Sub SyncLockOnWeakId3() 

         SyncLock "string" 
         End SyncLock 

      End Sub 

      Sub SyncLockOnWeakId4() 

         Dim member As MemberInfo = _
         SyncLock member
         End SyncLock 

      End Sub 

      Sub SyncLockOnWeakId5()

         Dim outOfMemory As New OutOfMemoryException()
         SyncLock outOfMemory
         End SyncLock 

      End Sub 

   End Class 

End Namespace