|Important||This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer|
Do not lock on objects with 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:
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 = _ Me.GetType().GetMember("SyncLockOnWeakId1")(0) SyncLock member End SyncLock End Sub Sub SyncLockOnWeakId5() Dim outOfMemory As New OutOfMemoryException() SyncLock outOfMemory End SyncLock End Sub End Class End Namespace