This rule raises if you acquire a lock with one of the following methods, and do not release it within the same method.

This rule will raise an issue when the code uses the disposable pattern. This pattern makes locking easy to use and delegates the responsibility to the caller. Users should accept issues in such cases, as they should appear only once for each synchronization type.

Why is this an issue?

Not releasing a lock in the same method where you acquire it, and releasing in another one, makes the code less clear and harder to maintain. You are also introducing the risk of not releasing a lock at all which can lead to deadlocks or exceptions.

Code examples

Noncompliant code example

Public Class Example

    Private Shared rwLock As New ReaderWriterLock

    Public Sub AcquireWriterLock()
        rwLock.AcquireWriterLock(2000)  ' Noncompliant, as the lock release is on the callers responsibility
    End Sub

    Public Sub DoSomething()
        ' ...
    End Sub

    Public Sub ReleaseWriterLock()
        rwLock.ReleaseWriterLock()
    End Sub

End Class

Compliant solution

Public Class Example

    Private Shared rwLock As New ReaderWriterLock

    Public Sub DoSomething()
        rwLock.AcquireWriterLock(2000)  ' Compliant, locks are released in the same method
        Try
            ' ...
        Finally
            rwLock.ReleaseWriterLock()
        End Try
    End Sub

End Class

Resources

Documentation