Bug 236 - TPL cannot use main UI thread TaskScheduler
Summary: TPL cannot use main UI thread TaskScheduler
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: unspecified
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Jérémie Laval
Depends on:
Reported: 2011-08-08 18:36 UTC by Jérémie Laval
Modified: 2011-08-11 07:08 UTC (History)
1 user (show)

Is this bug a regression?: ---
Last known good build:

Repro (4.92 KB, application/zip)
2011-08-08 18:36 UTC, Jérémie Laval

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Description Jérémie Laval 2011-08-08 18:36:17 UTC
Created attachment 92 [details]

In order to run some code off the UI thread, and some on, the TaskScheduler
"TaskScheduler.FromCurrentSynchronizationContext()" is used with a ContinueWith
of the background task.

However, either ContinueWith is broken or the UI TaskScheduler is broken
because such synchronized tasks end up executing on the background thread
instead of the main UI thread.

Steps to reproduce the problem:

            var t = Task.Factory.StartNew(() => {
                return 42;

            t.ContinueWith((r) => {

                // DO UI WORK ON UI THREAD

            }, TaskScheduler.FromCurrentSynchronizationContext());

There is an attached project that demos this bug. Watch the console output.
Comment 1 Jérémie Laval 2011-08-11 07:08:47 UTC
Fixed by toshok, see https://bugzilla.novell.com/show_bug.cgi?id=690944#c3