Bug EditorFreeze - BurstCompiler.CompileFunctionPointer (synchronous, 1.7.0)

I've upgraded project to Unity 2022.1.0f1, which auto-upgraded Burst package from 1.6.5 to 1.7.0.

When I enable SynchronousCompilation and try to compile any burst function with

BurstCompiler.CompileFunctionPointer

Editor freezes completely (10+ minutes waiting, then kill). There's no error in the log file.

When it actually happens?
- when called from

OnGUI

in EditorWindow
- when called from

Awake

in script on GameObject in scene, happens when entering Play Mode

When I upgrade to 1.7.1 or 1.8.0-pre.1, same issue.
When I downgrade to 1.6.5, everything works is fine.
So I'll be staying on 1.6.5 for now.

Why Synchronous compilation?
- I have some benchmarks comparing performance of Burst to .NET
- Sometimes I'm running profiler and want to make sure Burst is used

Why

CompileFunctionPointer

and not jobs?
- simplicity of benchmarks
- in few other cases it's faster: whole execution takes 0.005ms, job overhead as measured in 2021 was ~0.015ms

@xoofx Any idea what might be causing this?

 

I'm trying to create small repro project, but when I copy just the scripts with BurstCompile and all their dependencies it works. So it seems something else is influencing that...does anyone have any idea what might be an issue?

When I attach debugger and pause I can't see the Main thread, but I see that all 5 Burst compiler threads are waiting for work (ConcurrentQueue.Take) - I have six core CPU, so I'm guessing 5 threads is all of them.

The control flow enters

BurstCompiler.CompileFunctionPointer

, but never comes out (log calls before/after).

 

When I step-in with debugger, I can see that the freeze happens in

Unity.Burst.LowLevel.BurstCompilerService.CompileAsyncDelegateMethod

(external method implemented as free function in Unity Engine)

That's deepest I can get. There's screenshot from Thread window showing that compiler workers are doing nothing.


Native debugger screenshot, main thread is waiting for something:

 

No problem, logs attached

What I did:
1) Started UnityEditor (I've noticed message about burst logging in console)
2) Pressed Play
3) Editor froze
4) Waited couple minutes
5) Killed Editor
6) Grabbed log files

Burst tries to compile this method and freezes:

SubTriggerBox.RaycastBatch

This is probably what you're looking for:

Code (CSharp):

1. 2022-05-12 13:08:45.145 Handling request for `e9dea85fd1367d0216e33aa7e71b6c33` `SubTriggerBox, Volcanoids, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null::RaycastBatch(SubTriggerRaycast*, Volcanoids, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null|System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)` with options `--platform=Windows --backend=burst-llvm-12 --global-safety-checks-setting=On --dump=Function --float-precision=Standard --enable-synchronous-compilation --log-timings `
2. 2022-05-12 13:08:45.145 Storing function pointer request
3. 2022-05-12 13:08:45.146 Waiting synchronously for `e9dea85fd1367d0216e33aa7e71b6c33` `SubTriggerBox, Volcanoids, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null::RaycastBatch(SubTriggerRaycast*, Volcanoids, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null|System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)`

...and that's the end of the burst-client.log

 

Oh and there's bunch of these errors, seems like Burst has some problems when trying to find some methods in a assembly which contains unsafe code. Maybe it can't handle when there's TypedReference or other weird unsafe feature?

I mean I'm not expecting Burst to compile anything with TypedReference, but I'm expecting it not to crash when it compiles a method which is in the same assembly as other method which uses TypedReference.

I'll try to comment out certain parts of the code to confirm it.

Code (CSharp):

1. 2022-05-12 13:18:20.482 Executing job Find Methods (Samples.CosmeticDevice)
2. 2022-05-12 13:18:20.484 Using existing .bhc file for c:\Data\Projects\Volcanoids\Library\ScriptAssemblies\Samples.CosmeticDevice.dll with timestamp 5/12/2022 7:22:29 AM and GUID fb6c87b6-5107-4a57-888a-9b4ab88c6fcb
3. 2022-05-12 13:18:20.536 No existing .bhc file for c:\Data\Projects\Volcanoids\Library\ScriptAssemblies\Rock.Base.dll
4. 2022-05-12 13:18:20.574 Exception while executing job: System.AggregateException: One or more errors occurred. (Unimplemented Instruction RefAnyVal) ---> System.NotImplementedException: Unimplemented Instruction RefAnyVal
5.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher+InstructionHasher.DecodeInstruction (System.Reflection.Metadata.BlobReader& reader) [0x00509] in <660bf86525254f05bf0505fe2843d6a3>:0
6.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher.HashMethodDefinition (System.Reflection.Metadata.MethodDefinitionHandle methodDefinitionHandle, Burst.Compiler.IL.Hashing.CacheBuilder.Util.CachingMetadataReader metadataReader, System.Reflection.PortableExecutable.PEReader peReader, Burst.Compiler.IL.DebugInfo.PortablePdbInstance pdbInstance, Burst.Compiler.IL.Hashing.ILSignatureProvider signatureProvider, Burst.Compiler.IL.Hashing.Storage.BlobCollection blobCollection) [0x00086] in <660bf86525254f05bf0505fe2843d6a3>:0
7.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher+<>c__DisplayClass12_0.<HashImpl>b__4 (System.Reflection.Metadata.MethodDefinitionHandle methodDefinitionHandle, System.Threading.Tasks.ParallelLoopState loopState, System.Int64 i) [0x00000] in <660bf86525254f05bf0505fe2843d6a3>:0
8.                           at System.Threading.Tasks.Parallel+<>c__DisplayClass44_0`2[TSource,TLocal].<PartitionerForEachWorker>b__1 (System.Collections.IEnumerator& partitionState, System.Int32 timeout, System.Boolean& replicationDelegateYieldedBeforeCompletion) [0x00132] in <f4694e4600d74e03a4e35def8b97021c>:0
9.                         --- End of stack trace from previous location where exception was thrown ---
10.                        
11.                           at System.Threading.Tasks.Parallel+<>c__DisplayClass44_0`2[TSource,TLocal].<PartitionerForEachWorker>b__1 (System.Collections.IEnumerator& partitionState, System.Int32 timeout, System.Boolean& replicationDelegateYieldedBeforeCompletion) [0x0025f] in <f4694e4600d74e03a4e35def8b97021c>:0
12.                           at System.Threading.Tasks.TaskReplicator+Replica`1[TState].ExecuteAction (System.Boolean& yieldedBeforeCompletion) [0x00000] in <f4694e4600d74e03a4e35def8b97021c>:0
13.                           at System.Threading.Tasks.TaskReplicator+Replica.Execute () [0x00023] in <f4694e4600d74e03a4e35def8b97021c>:0
14.                            --- End of inner exception stack trace ---
15.                           at System.Threading.Tasks.TaskReplicator.Run[TState] (System.Threading.Tasks.TaskReplicator+ReplicatableUserAction`1[TState] action, System.Threading.Tasks.ParallelOptions options, System.Boolean stopOnFirstFailure) [0x0005b] in <f4694e4600d74e03a4e35def8b97021c>:0
16.                           at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal] (System.Collections.Concurrent.Partitioner`1[TSource] source, System.Threading.Tasks.ParallelOptions parallelOptions, System.Action`1[T] simpleBody, System.Action`2[T1,T2] bodyWithState, System.Action`3[T1,T2,T3] bodyWithStateAndIndex, System.Func`4[T1,T2,T3,TResult] bodyWithStateAndLocal, System.Func`5[T1,T2,T3,T4,TResult] bodyWithEverything, System.Func`1[TResult] localInit, System.Action`1[T] localFinally) [0x0017c] in <f4694e4600d74e03a4e35def8b97021c>:0
17.                         --- End of stack trace from previous location where exception was thrown ---
18.                        
19.                           at System.Threading.Tasks.Parallel.ThrowSingleCancellationExceptionOrOtherException (System.Collections.ICollection exceptions, System.Threading.CancellationToken cancelToken, System.Exception otherException) [0x0000b] in <f4694e4600d74e03a4e35def8b97021c>:0
20.                           at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal] (System.Collections.Concurrent.Partitioner`1[TSource] source, System.Threading.Tasks.ParallelOptions parallelOptions, System.Action`1[T] simpleBody, System.Action`2[T1,T2] bodyWithState, System.Action`3[T1,T2,T3] bodyWithStateAndIndex, System.Func`4[T1,T2,T3,TResult] bodyWithStateAndLocal, System.Func`5[T1,T2,T3,T4,TResult] bodyWithEverything, System.Func`1[TResult] localInit, System.Action`1[T] localFinally) [0x001db] in <f4694e4600d74e03a4e35def8b97021c>:0
21.                           at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal] (System.Collections.Generic.IEnumerable`1[T] source, System.Threading.Tasks.ParallelOptions parallelOptions, System.Action`1[T] body, System.Action`2[T1,T2] bodyWithState, System.Action`3[T1,T2,T3] bodyWithStateAndIndex, System.Func`4[T1,T2,T3,TResult] bodyWithStateAndLocal, System.Func`5[T1,T2,T3,T4,TResult] bodyWithEverything, System.Func`1[TResult] localInit, System.Action`1[T] localFinally) [0x00050] in <f4694e4600d74e03a4e35def8b97021c>:0
22.                           at System.Threading.Tasks.Parallel.ForEach[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Threading.Tasks.ParallelOptions parallelOptions, System.Action`3[T1,T2,T3] body) [0x0002a] in <f4694e4600d74e03a4e35def8b97021c>:0
23.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher.ParallelForEach[T] (System.Collections.Generic.IEnumerable`1[T] elements, System.Action`3[T1,T2,T3] callback) [0x00018] in <660bf86525254f05bf0505fe2843d6a3>:0
24.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher.HashImpl () [0x001c2] in <660bf86525254f05bf0505fe2843d6a3>:0
25.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher.HashAssembly (System.String filePath) [0x00007] in <660bf86525254f05bf0505fe2843d6a3>:0
26.                           at Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheLoader.CreateHashingResult (Mono.Cecil.AssemblyNameReference assemblyNameReference, Burst.Compiler.IL.AssemblyLoader assemblyLoader, Burst.Compiler.IL.Helpers.DebugLogWriter debugLogWriter) [0x00160] in <660bf86525254f05bf0505fe2843d6a3>:0
27.                           at Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheAssemblyStore.GetAssemblyState (System.String assemblyName, Burst.Compiler.IL.AssemblyLoader assemblyLoader) [0x000a7] in <660bf86525254f05bf0505fe2843d6a3>:0
28.                           at Burst.Compiler.IL.Server.EntryPointMethodFinder.LoadAllAssemblyReferences (Mono.Cecil.AssemblyDefinition asmDef, System.Collections.Generic.Dictionary`2[TKey,TValue] visited, System.Collections.Generic.Dictionary`2[TKey,TValue] jobProducers, Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheAssemblyStore assemblyStore, Burst.Compiler.IL.AssemblyLoader assemblyLoader) [0x00020] in <660bf86525254f05bf0505fe2843d6a3>:0
29.                           at Burst.Compiler.IL.Server.EntryPointMethodFinder.LoadAllAssemblyReferences (Mono.Cecil.AssemblyDefinition asmDef, System.Collections.Generic.Dictionary`2[TKey,TValue] visited, System.Collections.Generic.Dictionary`2[TKey,TValue] jobProducers, Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheAssemblyStore assemblyStore, Burst.Compiler.IL.AssemblyLoader assemblyLoader) [0x001de] in <660bf86525254f05bf0505fe2843d6a3>:0
30.                           at Burst.Compiler.IL.Server.EntryPointMethodFinder.LoadAllAssemblyReferences (Mono.Cecil.AssemblyDefinition asmDef, System.Collections.Generic.Dictionary`2[TKey,TValue] visited, System.Collections.Generic.Dictionary`2[TKey,TValue] jobProducers, Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheAssemblyStore assemblyStore, Burst.Compiler.IL.AssemblyLoader assemblyLoader) [0x001de] in <660bf86525254f05bf0505fe2843d6a3>:0
31.                           at Burst.Compiler.IL.Server.EntryPointMethodFinder.FindEntryPoints (System.String[] rootAssemblyNames, Burst.Compiler.IL.Hashing.CacheRuntime.HashCacheAssemblyStore assemblyStore, Burst.Compiler.IL.AssemblyLoader assemblyLoader, Burst.Compiler.IL.NativeCompilerOptions options, Burst.Compiler.IL.Server.ProfileDelegate profileCallback, Burst.Compiler.IL.Helpers.DebugLogWriter debugWriter) [0x00062] in <660bf86525254f05bf0505fe2843d6a3>:0
32.                           at Burst.Compiler.IL.Server.FindMethodsJob.Execute (Burst.Compiler.IL.Server.CompilerServerJobExecutionContext context) [0x0000c] in <660bf86525254f05bf0505fe2843d6a3>:0
33.                           at Burst.Compiler.IL.Server.CompilerThread.CompilerThreadLoop () [0x00103] in <660bf86525254f05bf0505fe2843d6a3>:0
34.                         ---> (Inner Exception #0) System.NotImplementedException: Unimplemented Instruction RefAnyVal
35.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher+InstructionHasher.DecodeInstruction (System.Reflection.Metadata.BlobReader& reader) [0x00509] in <660bf86525254f05bf0505fe2843d6a3>:0
36.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher.HashMethodDefinition (System.Reflection.Metadata.MethodDefinitionHandle methodDefinitionHandle, Burst.Compiler.IL.Hashing.CacheBuilder.Util.CachingMetadataReader metadataReader, System.Reflection.PortableExecutable.PEReader peReader, Burst.Compiler.IL.DebugInfo.PortablePdbInstance pdbInstance, Burst.Compiler.IL.Hashing.ILSignatureProvider signatureProvider, Burst.Compiler.IL.Hashing.Storage.BlobCollection blobCollection) [0x00086] in <660bf86525254f05bf0505fe2843d6a3>:0
37.                           at Burst.Compiler.IL.Hashing.CacheBuilder.ILHasher+<>c__DisplayClass12_0.<HashImpl>b__4 (System.Reflection.Metadata.MethodDefinitionHandle methodDefinitionHandle, System.Threading.Tasks.ParallelLoopState loopState, System.Int64 i) [0x00000] in <660bf86525254f05bf0505fe2843d6a3>:0
38.                           at System.Threading.Tasks.Parallel+<>c__DisplayClass44_0`2[TSource,TLocal].<PartitionerForEachWorker>b__1 (System.Collections.IEnumerator& partitionState, System.Int32 timeout, System.Boolean& replicationDelegateYieldedBeforeCompletion) [0x00132] in <f4694e4600d74e03a4e35def8b97021c>:0
39.                         --- End of stack trace from previous location where exception was thrown ---
40.                        
41.                           at System.Threading.Tasks.Parallel+<>c__DisplayClass44_0`2[TSource,TLocal].<PartitionerForEachWorker>b__1 (System.Collections.IEnumerator& partitionState, System.Int32 timeout, System.Boolean& replicationDelegateYieldedBeforeCompletion) [0x0025f] in <f4694e4600d74e03a4e35def8b97021c>:0
42.                           at System.Threading.Tasks.TaskReplicator+Replica`1[TState].ExecuteAction (System.Boolean& yieldedBeforeCompletion) [0x00000] in <f4694e4600d74e03a4e35def8b97021c>:0
43.                           at System.Threading.Tasks.TaskReplicator+Replica.Execute () [0x00023] in <f4694e4600d74e03a4e35def8b97021c>:0 <---
44.  

 

OK, I found it, when I modify this method like this, it works.

Code (CSharp):

1. public static TOut Reinterpret<TIn, TOut>(TIn value)
2. {
3.     //return __refvalue(__makeref(value), TOut);
4.     throw new NotImplementedException();
5. }

I'll delete cache and see if that works as different workaround.

 

Deleting cache does not help.

Since I've found what causes the issue, I'm okay with rewriting the method, there's no need to use TypedReference, it can be rewritten with

UnsafeUtility

I'm not sure whether Unity officially supports TypedReferences or not, but Burst should IMO at least ignore methods which use them and not crash. Especially when it's not needed at all for the code Burst is compiling / executing.

Thank you for help @sheredom, I wouldn't be able to figure it out without you.

 

@OndrejP According to this table, TypedReference is not supported only by IL2CPP, so I guess it should work in mono https://docs.unity3d.com/2022.2/Documentation/Manual/ScriptingRestrictions.html

Btw, its nice to learn something new, although it is hard to find any resources/documentation on TypedReferences. What is your use case of them?

 

Thanks, I had no idea TypedReference is mentioned there.

I used them mainly for casting generic type to concrete type in generic method/class.
Imagine you have generic method

DoSomething<T>

and you know that

T

is bool.
There's no way in C# to cast variable of type

T

to bool (without GC garbage or at least unsafe code).

So it was used in few rare cases when I wanted to branch in generic method for some special types.
Example:

if (type == typeof(bool)) return Utils.Reinterpret<bool, T>(true);

As I understand TypedReference, if I made error in the code and would accidentally cast variable to different type, it would throw exception.

Here's few other use cases:
https://stackoverflow.com/questions...he-scenes-its-so-fast-and-safe-almost-magical