Control.BeginInvoke(), which thread?

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  • Grandma Wilkerson

    #1

    Control.BeginInvoke(), which thread?

    My question concerns the documentation for Control.BeginIn voke(). At one
    point is says:

    "Executes the specified delegate asynchronously with the specified
    arguments, on the thread that the control's underlying handle was created
    on."

    later in that same documentation page it says...

    "Note The BeginInvoke method calls the specified delegate back on a
    different thread pool thread. You should not block a thread pool thread for
    any length of time."

    My impression was that when BeginInvoke is called on a control, the params
    are placed on the message queue of the UI thread [which created the control]
    and eventually the delegate representing the control's method is called *on
    the control's original UI thread*. Why does the documentation mention the
    thread pool? Why would a thread pool thread even be involved in this chain
    of events? I'm one confused granny.

    Granny


  • Bruce Brown

    #2
    Re: Control.BeginIn voke(), which thread?

    Hi,

    I cannot say anything about the documentation you are reading, but it is
    fairly simple.

    Control.BeginIn voke() executes the delegate from the UI thread.

    BeginInvoke calls on delegates execute the delegate from a thread in the
    thread pool. This is a standard asynchronous delegate call.

    Regards,

    - Bruce.


    "Grandma Wilkerson" <turd@bottlenec k.scalability.c rash.dum> wrote in message
    news:ul%23lLEzO DHA.560@TK2MSFT NGP10.phx.gbl.. .[color=blue]
    > My question concerns the documentation for Control.BeginIn voke(). At one
    > point is says:
    >
    > "Executes the specified delegate asynchronously with the specified
    > arguments, on the thread that the control's underlying handle was created
    > on."
    >
    > later in that same documentation page it says...
    >
    > "Note The BeginInvoke method calls the specified delegate back on a
    > different thread pool thread. You should not block a thread pool thread[/color]
    for[color=blue]
    > any length of time."
    >
    > My impression was that when BeginInvoke is called on a control, the params
    > are placed on the message queue of the UI thread [which created the[/color]
    control][color=blue]
    > and eventually the delegate representing the control's method is called[/color]
    *on[color=blue]
    > the control's original UI thread*. Why does the documentation mention the
    > thread pool? Why would a thread pool thread even be involved in this chain
    > of events? I'm one confused granny.
    >
    > Granny
    >
    >[/color]


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