[Transport] NetworkDriver.Concurrent.PopEventForConnection NullReferenceException

Hi all,

I'm getting the following exception from our implementation of the transport package. The exception only happens in build. In editor there are no errors. The exception only happens when a connection is made to the server. I have tried both scheduling the job and running it as seen from commented out code. When I schedule the job, the player crashes, when I run it I get the exception

Find the source for ServerUpdateJob and where I schedule/run it below

Transport 0.8.0-preview.8
Jobs 0.8.0-preview.23
Burst 1.5.3

Any tips on how I can debug this further would be greatly appreciated.

Cheers,
Andy

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2.   at Unity.Collections.NativeList`1[T].get_Length () [0x00001] in C:\BuildAgent\work\fb1ca7e713fe6fa1\Library\PackageCache\com.unity.collections@0.17.0-preview.18\Unity.Collections\NativeList.cs:225
3.   at Unity.Networking.Transport.NetworkDriver+Concurrent.PopEventForConnection (Unity.Networking.Transport.NetworkConnection connectionId, Unity.Networking.Transport.DataStreamReader& reader, Unity.Networking.Transport.NetworkPipeline& pipeline) [0x0000f] in C:\BuildAgent\work\fb1ca7e713fe6fa1\Library\PackageCache\com.unity.transport@0.8.0-preview.8\Runtime\NetworkDriver.cs:90
4.   at Unity.Networking.Transport.NetworkDriver+Concurrent.PopEventForConnection (Unity.Networking.Transport.NetworkConnection connectionId, Unity.Networking.Transport.DataStreamReader& reader) [0x00001] in C:\BuildAgent\work\fb1ca7e713fe6fa1\Library\PackageCache\com.unity.transport@0.8.0-preview.8\Runtime\NetworkDriver.cs:81
5.   at hugecalf.netcode.ServerUpdateJob.Execute () [0x00025] in C:\BuildAgent\work\fb1ca7e713fe6fa1\Packages\com.hugecalf.netcode\Runtime\ServerUpdateJob.cs:30
6.   at Unity.Jobs.IJobExtensions+JobStruct`1[T].Execute (T& data, System.IntPtr additionalPtr, System.IntPtr bufferRangePatchData, Unity.Jobs.LowLevel.Unsafe.JobRanges& ranges, System.Int32 jobIndex) [0x00001] in <19684f84c6314f4e90bb9f0493eb99b2>:0
7.   at (wrapper delegate-invoke) Unity.Jobs.IJobExtensions+JobStruct`1+ExecuteJobFunction[hugecalf.netcode.ServerUpdateJob].invoke_void_T&_intptr_intptr_JobRanges&_int(hugecalf.netcode.ServerUpdateJob&,intptr,intptr,Unity.Jobs.LowLevel.Unsafe.JobRanges&,int)
8. Unity.Jobs.LowLevel.Unsafe.JobsUtility:Schedule_Injected(JobScheduleParameters&, JobHandle&)
9. Unity.Jobs.LowLevel.Unsafe.JobsUtility:Schedule(JobScheduleParameters&)
10. Unity.Jobs.IJobExtensions:Run(ServerUpdateJob)
11. hugecalf.netcode.ServerNetPacketHandler:Process() (at C:\BuildAgent\work\fb1ca7e713fe6fa1\Packages\com.hugecalf.netcode\Runtime\Server.cs:129)
12. hugecalf.netcode.NetPacketHandler:Update() (at C:\BuildAgent\work\fb1ca7e713fe6fa1\Packages\com.hugecalf.netcode\Runtime\JobifiedNetPacketHandler.cs:84)
13. net.server.GameServer:Update() (at C:\BuildAgent\work\fb1ca7e713fe6fa1\Assets\Scripts\net\server\GameServer.cs:138)
14.  

Code (CSharp):

1. [BurstCompile]
2. public struct ServerUpdateJob : IJob {
3.     public NetworkDriver.Concurrent Driver;
4.     public NativeArray<NetworkConnection> Connections;
5.  
6.     public void Execute() {
7.         for (var i = 0; i < Connections.Length; i++) {
8.             var connection = Connections[i];
9.             Assert.IsTrue(connection.IsCreated);
10.  
11.             NetworkEvent.Type command;
12.             while ((command = Driver.PopEventForConnection(connection, out var reader)) != NetworkEvent.Type.Empty) {
13.                 if (command == NetworkEvent.Type.Data) {
14.                     //on data
15.                 }
16.                 else if (command == NetworkEvent.Type.Disconnect) {
17.                     Connections[i] = default;
18.                 }
19.             }
20.         }
21.     }
22. }

Code (CSharp):

1. jobHandle.Complete();
2.  
3. var connectionJob = new ServerConnectionsUpdateJob {
4.     Driver = driver,
5.     Connections = connections,
6.     NewConnections = newConnections
7. };
8.          
9. var updateJob = new ServerUpdateJob {
10.     Driver = concurrentDriver,
11.     Connections = connections.AsDeferredJobArray(),
12. };
13.  
14. jobHandle = driver.ScheduleUpdate(jobHandle);
15. jobHandle = connectionJob.Schedule(jobHandle);
16.          
17. // jobHandle = updateJob.Schedule(jobHandle);
18. jobHandle.Complete();
19. updateJob.Run();
20. jobHandle = ScheduleDeserialise(jobHandle);

Code (CSharp):

1. connections = new NativeList<NetworkConnection>(MaxConnections, Allocator.Persistent);

 

Thanks @timjohansson, I didn't know there was a dedicated transport forum - will post here in future

THIS sounds likely, as I made the very "wise" move to cache the call to ToConcurrent after creating the driver. I will reevaluate it every time it is needed, make a build and test

I will also look into that AsDeferredJobArray() call, as I have adapted my code from the example which does use IJobParallelForDefer. Thinking about it though, doesn't the conversion to the NativeArray does still need to be deferred until the job actually runs? Maybe I misunderstand.

Cheers!

 

Yep that has done the trick, thanks a lot!