small bugfixes and add tmux ssh session for interactive debugging

.github/workflows/R-CMD-check.yaml

@@ -37,8 +37,9 @@ jobs:
       TORCH_TEST: 1
       TORCH_INSTALL: 1
       TORCH_COMMIT_SHA: "none"
+      OMP_NUM_THREADS: 1
+      MKL_NUM_THREADS: 1
       PYTORCH_ENABLE_MPS_FALLBACK: 1
-      PYTORCH_MPS_HIGH_WATERMARK_RATIO: 0.0
 
     steps:
       - uses: actions/checkout@v3
@@ -65,13 +66,24 @@ jobs:
         run: keras::install_keras()
         shell: Rscript {0}
 
+      # Get a tmux ssh session for interactive debugging
+      # Controlled via inputs from GitHub webinterface
+      # See https://github.com/mxschmitt/action-tmate
+      - name: Setup tmate session
+        uses: mxschmitt/action-tmate@v3
+        if: ${{ github.event_name == 'workflow_dispatch' && inputs.debug_enabled }}
+
       - name: Check if torch is installed
         run: |
           library(torch)
           if (!torch_is_installed()) {
             print("Torch is not installed!")
             install_torch()
           }
+          if (torch::backends_mps_is_available()) {
+            print("LibTorch is built with MPS support!")
+          }
+          print(paste0("Default number of threads: ", torch_get_num_threads()))
           print(torch_randn(1))
         shell: Rscript {0}