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Application Idle - Good or bad practice?Hi All,
What do you know about the Application.Idle event? When is it a good practice to use it and when should I not use it? I know it fires when the app message queue is empty, and that this happens a lot. But if I register many handlers on this event, what impact will it have on my application? Is it true to say that it doesn't impact my application performances becuase the queue is empty anyhow? Thanks! "Udi" <UdiBenSen***@gmail.com> wrote in message It depends largely on what your handlers are doing, as long as they don't news:1141955310.024197.271350@p10g2000cwp.googlegroups.com... | Hi All, | What do you know about the Application.Idle event? | When is it a good practice to use it and when should I not use it? | I know it fires when the app message queue is empty, and that this | happens a lot. | But if I register many handlers on this event, what impact will it have | on my application? | Is it true to say that it doesn't impact my application performances | becuase the queue is empty anyhow? | Thanks! | block the message pump you are safe, but once you are start computational intensive tasks you might disturb the message pump and this will have an impact on the responsiveness of the main UI. Willy. Thanks Willy,
So just to understand, if I have lots of very short handlers I'm ok? Do they have lower priority than the main UI messages? (What happens if i have registered say 5 handlers on App.idle, 3 are dealt, and than comes a message from the main UI? Will the remaining 2 handlers be executed first on the next idle? will they be ignored?) - Or, once the app.idle is fired, it will execute all of it's handlers, and only after executing all of them it returns the control back to the main UI queue? Udi wrote:
> Thanks Willy, The latter is my understanding of how it works. Once it fires, it will > So just to understand, if I have lots of very short handlers I'm ok? > Do they have lower priority than the main UI messages? > (What happens if i have registered say 5 handlers on App.idle, 3 are > dealt, and than comes a message from the main UI? Will the remaining 2 > handlers be executed first on the next idle? will they be ignored?) > - Or, once the app.idle is fired, it will execute all of it's handlers, > and only after executing all of them it returns the control back to the > main UI queue? execute all handlers before returning. Note also that this fires just before the thread becomes idle. -- Tom Porterfield "Udi" <UdiBenSen***@gmail.com> wrote in message The handler runs on the UI thread, that means that it runs at the same news:1142031940.115523.81630@e56g2000cwe.googlegroups.com... | Thanks Willy, | So just to understand, if I have lots of very short handlers I'm ok? | Do they have lower priority than the main UI messages? | (What happens if i have registered say 5 handlers on App.idle, 3 are | dealt, and than comes a message from the main UI? Will the remaining 2 | handlers be executed first on the next idle? will they be ignored?) | - Or, once the app.idle is fired, it will execute all of it's handlers, | and only after executing all of them it returns the control back to the | main UI queue? | priority and as long as your handler runs, it blocks the processing of new messages. Note that it's possible to interrupt the handler by pumping the queue (DoEvents or similar) so that you don't block the message queue while running time consuming handlers (reminds me of 16 bit Windows, shiver...). All handlers will get executed supposed no new messages are waiting in the system queue. When an handler returns, the framework code pumps the queue and when a new message arrived, it will handle that message (subject of message priorities AFAIK) before invoking the next handler. Willy.  
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