topic Re: ArcGIS Pro 3.3.4 QueuedTask.Run throws an ERROR TaskStatus.WaitingForActivation. in ArcGIS Pro SDK Questions

ArcGIS Pro 3.3.4 QueuedTask.Run throws an ERROR TaskStatus.WaitingForActivation.

RichardDaniels — Wed, 26 Feb 2025 18:57:00 GMT

Has anyone encountered this issue and have a better work around?

Many of the commonly used methods in ArcGIS Pro SDK are required to be run on the 'MCT' thread. The code is wrapped in a QueuedTask.Run block and in most cases, we need to Wait for the result before continuing processing. This is often done with Task.Wait(). However, I've recently ran into a situation where Task.Wait throws an ERROR because the task has a status of TaskStatus.WaitingForActivation. Is this a known issue?

Task t1 = QueuedTask.Run(() =>
{

try { //do some long running work }

catch (Exception eX) { // handle the error }

});

//code added to prevent error

while (t1.Status==TaskStatus.WaitingForActivation)
{
Thread.Sleep(500);
loopCount++;
if (loopCount > 22) // 11 seconds max wait time
{
break;
}
}

if (t1.Status==TaskStatus.WaitingForActivation) { throw new exception("Task failed to Start within 11 seconds."); }

t1.Wait();

Re: ArcGIS Pro 3.3.4 QueuedTask.Run throws an ERROR TaskStatus.WaitingForActivation.

UmaHarano — Thu, 27 Feb 2025 22:24:27 GMT

A comment pattern to await the QueudTask is to use the await key word.

Task t1 = await QueuedTask.Run(() => { try { //do some long running work } catch (Exception eX) { // handle the error } });

A good resource that documents Pro's Asynchronous programming concepts is available in this wiki:

ProConcepts: Asynchronous Programming in ArcGIS-Pro

Re: ArcGIS Pro 3.3.4 QueuedTask.Run throws an ERROR TaskStatus.WaitingForActivation.

RichardDaniels — Thu, 27 Feb 2025 22:40:09 GMT

In you example if we had a line 9, that did more work (e.g., getting t2.Result), would your code Wait till the task is completed before running line 9?

Re: ArcGIS Pro 3.3.4 QueuedTask.Run throws an ERROR TaskStatus.WaitingForActivation.

RichardDaniels — Thu, 27 Feb 2025 22:45:44 GMT

But await does not actually cause the code to Wait 🙂