Late Tick Event on Timer Object

Question

We are experiencing a problem with a Tick() event being processed by an
event loop approximately 15 minutes after the event is posted. We have a
method on one of our service objects that looks something like this:
iTimer : Timer = new(IsActive = FALSE);
event loop
postregister
iTimer.WaitUntil(self.GetNextTime());
iTimer.IsActive = TRUE;
when iTimer.Tick do
iTimer.IsActive = FALSE;
self.Cleanup();
iTimer.WaitUntil(self.GetNextTime());
iTimer.IsActive = TRUE;
when task.Shutdown do
exit;
end event;
iTimer.IsActive = FALSE;
The GetNextTime() method returns a DateTimeData object that is always set to
the earliest midnight of the future. Has anyone seen this type of behaviour
before? Any suggestions as to the cause of the problem?
Thanks in advance for your help.
Neil Willems
SED Systems Inc.
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Answer 1

Hello Tom,
> Maybe the operations are being run on a background thread and then keep having to jump into the main thread to access the email items...?
You shouldn't use another threads when dealing with the Outlook object model. Office applications use the single threaded apartment (STA) model and don't support multithreading. All calls made from another threads are marshalled by Outlook to the main
thread. However, you can use a low-level code (Extended MAPI) to access the data from secondary threads. For example, you can use Redemption which is based on Extended MAPI.
>  it loops through everything quite quickly (~12,000 emails in 30 secs)
Instead of looping over all items in the folder I'd recommend using the
Find/FindNext
or
Restrict methods of the Items class. You can read more about them in the following articles:
How To: Use Find and FindNext methods to retrieve Outlook mail items from a folder (C#, VB.NET)
How To: Use Restrict method to retrieve Outlook mail items from a folder
You can use the System.Windows.Forms.Timer class which uses the main thread for invoking the Tick event. The .NET
Framework Class Library provides three different timer classes: System.Windows.Forms.Timer, System.Timers.Timer, and System.Threading.Timer. Each of these classes has been designed and optimized for use in different situations. The Comparing
the Timer Classes in the .NET Framework Class Library article examines the three timer classes and helps you gain an understanding of how and when each class should be used.
Also you may find the
AdvancedSearch method of the Application class helpful. Pay special attention to the fact that the search is performed in another thread. You don’t need to run another thread manually since the
AdvancedSearch method runs it automatically in the background. See
Advanced search in Outlook programmatically: C#, VB.NET for more information.