Fixes a dead lock in the effect system

The `DynamicEffectInstance` does a blocking wait on the result of the effect system. In there a continuation is created in case the compilation task is not yet finished. In case that continuation got scheduled on the calling thread we ended up in a dead lock. See also TheFuseLab/VL.Fuse#51
chaouanabil · Oct 21, 2021 · 25710ee · 25710ee
1 parent 2887398
commit 25710ee
Showing 1 changed file with 3 additions and 5 deletions.
diff --git a/sources/engine/Stride.Rendering/Rendering/EffectSystem.cs b/sources/engine/Stride.Rendering/Rendering/EffectSystem.cs
@@ -158,13 +158,11 @@ public TaskOrResult<Effect> LoadEffect(string effectName, CompilerParameters com
 
             if (bytecode.Task != null && !bytecode.Task.IsCompleted)
             {
-                // Result was async, keep it async
-                // NOTE: There was some hangs when doing ContinueWith() (note: it might switch from EffectPriorityScheduler to TaskScheduler.Default, maybe something doesn't work well in this case?)
-                //       it seems that TaskContinuationOptions.ExecuteSynchronously is helping in this case (also it will force continuation to execute right away on the thread pool, which is probably better)
-                //       Not sure if the probably totally disappeared (esp. if something does a ContinueWith() externally on that) -- might need further investigation.
+                // Ensure the continuation is scheduled on the thread pool or we might end up in a dead lock when then calling thread
+                // is already waiting on the result
                 var result = bytecode.Task.ContinueWith(
                     x => CreateEffect(effectName, x.Result, compilerResult),
-                    TaskContinuationOptions.ExecuteSynchronously);
+                    scheduler: TaskScheduler.Default);
                 return result;
             }
             else