Thread and message pump




If I run a classical Windows Form .Net application, with several UI
controls/windows, I guess that (unless I explicitely create new threads)
every UI objects will have the same message pump (since they all have been
created by the same thread). Correct ?

My point is that when we speak about the "UI thread", I don't know if we
speak about the thread which owns the message pump or about the thread which
updates the UI. I want to be sure that this thread does both.

Best regards



As i know control members can be accessed only from the thread that created
it(otherwise You have to Invoke), so at the end the "thread which updates
the UI" is the same as the thread which owns the control.

Hope You find this useful.

Linda Liu[MSFT]

Hi Oriane,

Yes, every UI object will have the same message pump.

Message pump is also called message queue. The system automatically creates
a message queue for each thread in an application.

If the thread creates one or more windows, a message loop must be provided;
this message loop retrieves messages from the thread's message queue and
dispatches them to the appropriate window procedures.

In WinForm applications, we call Application.Run method to run a standard
application message loop on the current thread.
when we speak about the "UI thread", I don't know if we speak about the
thread which owns the message pump or about the thread which
updates the UI.

The "UI thread" refers to the thread that creates forms and controls on the
forms and that updates the UI.

Hope I make things clear.
If you have any question, please feel free to let me know.

Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
(e-mail address removed).

Get notification to my posts through email? Please refer to

Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
This posting is provided "AS IS" with no warranties, and confers no rights.

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question