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Fix native library loader silently failing when CUDA DLLs are missing #1555

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Fix native library loader silently failing when CUDA DLLs are missing #1555

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c7f1271
Fix native library loader silently failing when CUDA DLLs are missing
alinpahontu2912 Mar 20, 2026
f1c93e4
Update src/TorchSharp/Torch.cs
alinpahontu2912 Mar 20, 2026
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40 changes: 20 additions & 20 deletions src/TorchSharp/Torch.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,7 @@ private static void LoadNativeBackend(bool useCudaBackend, out StringBuilder? tr
trace = null;

if (!alreadyLoaded) {
bool ok;
bool ok = true;
trace = new StringBuilder();
trace.AppendLine($"");
trace.AppendLine($"TorchSharp: LoadNativeBackend: Initialising native backend, useCudaBackend = {useCudaBackend}");
Expand All @@ -134,30 +134,30 @@ private static void LoadNativeBackend(bool useCudaBackend, out StringBuilder? tr
// Preloading these DLLs on windows seems to iron out problems where one native DLL
// requests a load of another through dynamic linking techniques.
//
ok = TryLoadNativeLibraryByName("cudnn_adv64_9", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_cnn64_9", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_ops64_9", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_graph64_9.dll", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_heuristic64_9.dll", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_engines_precompiled64_9.dll", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cudnn_engines_runtime_compiled64_9.dll", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("nvrtc-builtins64_128", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("caffe2_nvrtc", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("nvrtc64_120_0", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cublasLt64_12", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cufft64_11", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cusparse64_12", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("cusolver64_11", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_adv64_9", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_cnn64_9", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_ops64_9", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_graph64_9.dll", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_heuristic64_9.dll", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_engines_precompiled64_9.dll", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cudnn_engines_runtime_compiled64_9.dll", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("nvrtc-builtins64_128", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("caffe2_nvrtc", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("nvrtc64_120_0", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cublasLt64_12", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cufft64_11", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cusparse64_12", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("cusolver64_11", typeof(torch).Assembly, trace);
}

ok = TryLoadNativeLibraryByName("torch_cuda", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("LibTorchSharp", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("torch_cuda", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("LibTorchSharp", typeof(torch).Assembly, trace);
} else {
ok = TryLoadNativeLibraryByName("torch_cpu", typeof(torch).Assembly, trace);
ok = TryLoadNativeLibraryByName("LibTorchSharp", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("torch_cpu", typeof(torch).Assembly, trace);
ok &= TryLoadNativeLibraryByName("LibTorchSharp", typeof(torch).Assembly, trace);
}

trace.AppendLine($" Result from regular native load of LibTorchSharp is {ok}");
trace.AppendLine($" Result from regular native load of backend libraries (CUDA preloads + torch_* + LibTorchSharp) is {ok}");

// Try dynamic load from package directories
if (!ok) {
Expand Down