Task.Run hang in unity relative with il2cpp

hello.

my project use heavy network using ssl stream in unity

and some random case task.run get hang in MobileAuthenticatedStream.cs below line

Code (CSharp):

1. int num = await (!sync ? authenticatedStream.InnerStream.ReadAsync(authenticatedStream.readBuffer.Buffer, authenticatedStream.readBuffer.EndOffset, len, cancellationToken) : (Task<int>) Task.Run<int>((Func<M0>) (() => this.InnerStream.Read(this.readBuffer.Buffer, this.readBuffer.EndOffset, len)))).ConfigureAwait(false);

im digging to find what the problem is

and it's il2cpp related problem

the task not dispatch in threadPoolWorkerQueue.cs

cause memory barrier in ios

i change the il2cpp code in xcode for LocalPop and TryStreal like below

LocalPop function

Code (CSharp):

1.  
2. Interlocked_Exchange_mD5CC61AF0F002355912FAAF84F26BE93639B5FD5((int32_t*)L_7,
3.           ((int32_t)il2cpp_codegen_add((int32_t)L_8, (int32_t)1)), /*hidden argument*/NULL);
4. il2cpp_codegen_memory_barrier();
5. int32_t L_9 = V_1;
6. int32_t L_10 = __this->get_m_tailIndex_3();
7. il2cpp_codegen_memory_barrier();
8. if ((((int32_t)L_9) >= ((int32_t)L_10)))
9.  

TrySteal function

Code (CSharp):

1.  
2.  
3. Interlocked_Exchange_mD5CC61AF0F002355912FAAF84F26BE93639B5FD5((int32_t*)L_5, L_6, /*hidden argument*/NULL);
4. il2cpp_codegen_memory_barrier();
5. int32_t L_7 = __this->get_m_headIndex_2();
6. il2cpp_codegen_memory_barrier();
7. int32_t L_8 = V_0;
8. if ((((int32_t)L_7) > ((int32_t)L_8)))
9.  

i insert the barrier right after the Interlocked_Exchange

then problem disappear

so ios build is ok

but android can't modify the cpp file


How could I solve this problem?

please help me out.

thanks a lot

 

is it possible to report about ios device?

i just print out the head, and tail index for this https://referencesource.microsoft.com/#mscorlib/system/threading/threadpool.cs,149
when it hang on

i think head index shouldn't be get larger than tail index so localPop and TryStreal cannot get the same task

but it success when localPop and TryStreal go throught at same time so twice pop the task and header index get bigger than tail index

below is footprint of localPush, localPop, TryStreal

first one is thread_id, next is task address, then head and tail index

Code (CSharp):

1.  
2. localPush            1741748, 0x13f1a7f60,    563,564
3. localPop              1741748, 0x13f1a7f60,    564,563,563,563
4. TrySteal               1741747, 0x13f1a7f60,    564,563,563,564
5.  

number 564,563,563,563 order by

__this.get_m_headIndex_2(), __this.get_m_tailIndex_2(), L_9(head), L_10(tail)

you can see the L_9, L_10 is true on if statement https://referencesource.microsoft.com/#mscorlib/system/threading/threadpool.cs,312
to get task and right after print it out from this pointer

the head index is bigger then tail index but head index shouldn't be change.

so i think the Interlocked.Exchange on ios not guarantee the memory barrier




it has same problem on android but window didn't

thanks a lot

 

submit a reporting is done

https://fogbugz.unity3d.com/default.asp?1299421_v59rpnr2bmcg90v9

thanks a lot

 

@JoshPeterson have you reproducer the bug that i report?