[Genhis] [2.0.43] OSX only hang in mapgen code

[cliff_build]

What did you do?

I played a multiplayer game with the Warp-Drive-Machine mod with some windows PCs and an OSX (M1/arm64) laptop.

What happened?

The OSX factorio instance hangs soon after landing on a new planet. The windows instances work just fine.

What did you expect to happen instead? It might be obvious to you, but do it anyway!

I expected all clients to behave the same way (and ideally not hang).

Does it happen always, once, or sometimes?

I have a save that reproduces this problem (attached).

I did some amount of debugging attempts. When factorio is hung in this state, it is using 1 CPU worth of resources, and running commands like

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sudo sample 3236 10 -file /tmp/factorio_sample2.txt

gives output that includes the following (which implies to me that the game is busy doing some sort of map generation code). I don't know a lot about Warp Drive Machine, but this is just after the ship landed on a new alien-biomes planet. Notice that the sampled stacks do not have any lua code running that I can see.

I have not tried loading the save on linux, so I don't know whether it works there or not.

I am willing to do work to try and help debug, including changing the mod code. I'd love to at least have some understanding of what I should even be looking for though. I don't really understand what would cause infinite-map-generation.

Note that in the attached save, the game actually hangs a tiny bit after loading (maybe 30 ticks or something).

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    8360 Thread_37889358: MapGenerationHelper
      8360 thread_start  (in libsystem_pthread.dylib) + 8  [0x185cef0fc]
        8360 _pthread_start  (in libsystem_pthread.dylib) + 136  [0x185cf42e4]
          8360 std::__thread_proxy[abi:v160006]<std::tuple<std::unique_ptr<std::__thread_struct>, void (MapGenerationHelper::*)(), MapGenerationHelper*>>(void*)  (in factorio) + 72  [0x106c689f>
            8360 MapGenerationHelper::consumeTasks()  (in factorio) + 484  [0x106001f80]  MapGenerationHelper.cpp:153
              8360 EntityMapGenerationTask::compute()  (in factorio) + 52  [0x105fdfba4]  EntityMapGenerationTask.cpp:111
                8360 EntityMapGenerationTask::computeInternal()  (in factorio) + 104  [0x105fdfc70]  EntityMapGenerationTask.cpp:134
                  8357 Noise::multioctaveNoise(float, float, unsigned int, unsigned int, float, float, float, float, float, NoiseScratch&, float*) const  (in factorio) + 332  [0x1060f5e84]  Noi>
                  ! 3516 Noise::noise(float, float, unsigned int, unsigned int, float, float, float, NoiseScratch&, float*) const  (in factorio) + 900,904,...  [0x1060f57bc,0x1060f57c0,...]  No>
                  ! 2044 Noise::noise(float, float, unsigned int, unsigned int, float, float, float, NoiseScratch&, float*) const  (in factorio) + 864,836,...  [0x1060f5798,0x1060f577c,...]  No>
                  ! 969 Noise::noise(float, float, unsigned int, unsigned int, float, float, float, NoiseScratch&, float*) const  (in factorio) + 888,884,...  [0x1060f57b0,0x1060f57ac,...]  Noi>

[StrangePan]

Hi, is this the correct save? It doesn't seem to have any of the mods that are listed in your log file.

[cliff_build]

I'm so sorry, it was not the correct save. This is the correct one.

[StrangePan]

No problem! We were able to reproduce the issue with the new save you sent us.

[Genhis]

Thanks, the save file helped! The problem in map generation was caused by undefined behavior when casting infinity (float) to unsigned integer. For 2.0.49, I added more checks around this place and it will throw an exception if `MultioctaveNoise::octaves` is negative or infinite. Old saves will get a migration, but the mod author will have to fix map generation on their end. Most likely it's a division by zero somewhere in noise expressions which causes the octaves value to be infinite.