I would like to know why locking on a new object takes significantly
longer than locking on a strongly typed object. All of the posts I've
seen say that it is best to lock on a "new object", but it takes more
than 3x longer than locking on anything other than object. Here's a
test case:
Module Module1
Sub Main()
Dim T As clsTest
Dim i As Integer
Dim D As Date
Const MAX = 10000000
Dim LL As New Object
Dim DTest As Date
Dim T2 As New clsDummy
T = New clsTest
D = Now
For i = 1 To MAX
T.Index += 1
Next
Console.WriteLi ne("No lock: " & Now.Ticks - D.Ticks)
T = New clsTest
D = Now
For i = 1 To MAX
SyncLock T
T.Index += 1
End SyncLock
Next
Console.WriteLi ne("Lock on owner: " & Now.Ticks - D.Ticks)
T = New clsTest
D = Now
For i = 1 To MAX
SyncLock LL
T.Index += 1
End SyncLock
Next
Console.WriteLi ne("Lock on new object: " & Now.Ticks - D.Ticks)
T = New clsTest
D = Now
For i = 1 To MAX
SyncLock T2
T.Index += 1
End SyncLock
Next
Console.WriteLi ne("Lock on Dummy object: " & Now.Ticks -
D.Ticks)
Console.ReadLin e()
End Sub
Class clsDummy
End Class
Class clsTest
Dim m_Index As Integer
Public Property Index() As Integer
Get
Return m_Index
End Get
Set(ByVal Value As Integer)
m_Index += 1
End Set
End Property
End Class
thanks,
Keith
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Keith, I would like to know why locking on a new object takes significantly longer than locking on a strongly typed object.
Because on each iteration there's a call to
Microsoft.Visua lBasic.Compiler Services.FlowCo ntrol.CheckForS yncLockOnValueT ype()
which throws an exception if you're trying to lock on a boxed value
type, because that isn't allowed in VB.
All of the posts I've seen say that it is best to lock on a "new object", but it takes more than 3x longer than locking on anything other than object.
I bet all those posts used it in more realistic situations though. For
a one time lock, the perf difference hardly matters. I hope you don't
have real code that looks like what you posted.
Mattias
--
Mattias Sjögren [MVP] mattias @ mvps.org http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.
Mattias,
Obviously this was just a test case to demonstrate the differences,
and not real code. In light of the performance difference, doesn't it
make more sense to use an empty custom class instead of a generic
object?
Keith
Mattias Sjögren <ma************ ********@mvps.o rg> wrote in message news:<#$******* *******@TK2MSFT NGP09.phx.gbl>. .. Keith,
I would like to know why locking on a new object takes significantly longer than locking on a strongly typed object.
Because on each iteration there's a call to
Microsoft.Visua lBasic.Compiler Services.FlowCo ntrol.CheckForS yncLockOnValueT ype()
which throws an exception if you're trying to lock on a boxed value type, because that isn't allowed in VB.
All of the posts I've seen say that it is best to lock on a "new object", but it takes more than 3x longer than locking on anything other than object.
I bet all those posts used it in more realistic situations though. For a one time lock, the perf difference hardly matters. I hope you don't have real code that looks like what you posted. Mattias
Keith, In light of the performance difference, doesn't it make more sense to use an empty custom class instead of a generic object?
Personally I wouldn't bother. At least not unless the code was in a
tight loop or something and profiling the code showed that it was a
bottleneck and needed some extra perf boost.
Mattias
--
Mattias Sjögren [MVP] mattias @ mvps.org http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: Keith Langer |
last post by:
I would like to know why locking on a new object takes significantly
longer than locking on a strongly typed object. All of the posts I've
seen say that it is best to lock on a "new object", but it takes more
than 3x longer than locking on anything other than object. Here's a
test case:
Module Module1
Sub Main()
|
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last post by:
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Thanks
Fred
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