More robust environment installs for ASV benchmarks

.github/workflows/asv-benchmarking-pr.yml

@@ -43,6 +43,14 @@ jobs:
             python-build
             mamba
 
+      # asv rebuilds its own env under benchmarks/env/ each run; caching skips the
+      # solve. No restore-keys: asv reuses a restored env without checking it.
+      - name: Cache asv environment
+        uses: actions/cache@v6
+        with:
+          path: ${{ env.ASV_DIR }}/env
+          key: "asv-env-${{runner.os}}-${{runner.arch}}-${{hashFiles(env.CONDA_ENV_FILE, 'benchmarks/asv.conf.json')}}"
+
       - name: Run Benchmarks
         shell: bash -l {0}
         id: benchmark

benchmarks/asv.conf.json

@@ -34,7 +34,12 @@
 
     // Customizable commands for installing and uninstalling the project.
     // See asv.conf.json documentation.
-    // "install_command": ["in-dir={env_dir} python -mpip install {wheel_file}"],
+    //
+    // --no-deps: conda already installed every dependency from ci/environment.yml.
+    // --force-reinstall is asv's default; the version may not change (asv gh-1421).
+    "install_command": [
+        "in-dir={env_dir} python -m pip install {wheel_file} --no-deps --force-reinstall"
+    ],
     // "uninstall_command": ["return-code=any python -mpip uninstall -y {project}"],
 
     // List of branches to benchmark. If not provided, defaults to "master"
@@ -57,6 +62,10 @@
     "environment_type": "conda",
     "conda_channels": ["conda-forge"],
 
+    // Same package set as the rest of CI, so benchmarks cannot drift from it:
+    // #1548 made cartopy, matplotlib and spatialpandas optional and broke two.
+    "conda_environment_file": "../ci/environment.yml",
+
     // timeout in seconds for installing any dependencies in environment
     // defaults to 10 min
     "install_timeout": 600,
@@ -90,10 +99,12 @@
     // new environments.  A value of ``null`` means that the variable
     // will not be set for the current combination.
     //
+    // Only what ci/environment.yml lacks: the build tools, which asv seeds itself
+    // only when building an environment without a file, plus pyfma from PyPI.
      "matrix": {
+        "python-build": [""],
+        "wheel": [""],
         "setuptools_scm": [""],
-        "xarray": [""],
-        "netcdf4": [""],
         "pip+pyfma": [""]
     },