Run diff / bench in parallel

Author: antonmedv

.github/workflows/diff.yml

@@ -5,28 +5,61 @@ on:
     branches: [ master ]
 
 jobs:
-  bench:
+  benchmark:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ref: [master, ${{ github.sha }}]
+        include:
+          - ref: master
+            name: old
+          - ref: ${{ github.sha }}
+            name: new
     steps:
       - name: Setup Go 1.18
         uses: actions/setup-go@v4
         with:
           go-version: 1.18
+
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ matrix.ref }}
+
+      - name: Run benchmark
+        run: go test -bench=. -benchmem -run=^$ -count=10 -timeout=30m | tee /tmp/${{ matrix.name }}.txt
+
+      - name: Upload benchmark results
+        uses: actions/upload-artifact@v3
+        with:
+          name: benchmark-${{ matrix.name }}
+          path: /tmp/${{ matrix.name }}.txt
+
+  compare:
+    needs: benchmark
+    runs-on: ubuntu-latest
+    steps:
+      - name: Setup Go 1.18
+        uses: actions/setup-go@v4
+        with:
+          go-version: 1.18
+
       - name: Install benchstat
         # NOTE: benchstat@latest requires go 1.23 since 2025-02-14 - this is the last go 1.18 ref
         # https://cs.opensource.google/go/x/perf/+/c95ad7d5b636f67d322a7e4832e83103d0fdd292
         run: go install golang.org/x/perf/cmd/benchstat@884df5810d2850d775c2cb4885a7ea339128a17d
 
-      - uses: actions/checkout@v3
-      - name: Benchmark new code
-        run: go test -bench=. -benchmem -run=^$ -count=10 -timeout=30m | tee /tmp/new.txt
+      - name: Download old benchmark results
+        uses: actions/download-artifact@v3
+        with:
+          name: benchmark-old
+          path: /tmp/
 
-      - name: Checkout master
-        uses: actions/checkout@v3
+      - name: Download new benchmark results
+        uses: actions/download-artifact@v3
         with:
-          ref: master
-      - name: Benchmark master
-        run: go test -bench=. -benchmem -run=^$ -count=10 -timeout=30m | tee /tmp/old.txt
+          name: benchmark-new
+          path: /tmp/
 
-      - name: Diff
+      - name: Compare benchmarks
         run: benchstat /tmp/old.txt /tmp/new.txt