fix(router): do not reuse planners in the plan generator

router/pkg/plan_generator/plan_generator.go

@@ -120,13 +120,6 @@ func PlanGenerator(ctx context.Context, cfg QueryPlanConfig) error {
 	for i := 0; i < cfg.Concurrency; i++ {
 		go func(i int) {
 			defer wg.Done()
-			planner, err := pg.GetPlanner()
-			if err != nil {
-				// if we fail to get the planner, we need to cancel the context to stop the other goroutines
-				// and return here to stop the current goroutine
-				cancelError(fmt.Errorf("failed to get planner: %v", err))
-				return
-			}
 			for {
 				select {
 				case <-ctxError.Done():
@@ -146,6 +139,15 @@ func PlanGenerator(ctx context.Context, cfg QueryPlanConfig) error {
 
 					queryFilePath := filepath.Join(queriesPath, queryFile.Name())
 
+					// Planners should not be reused.
+					planner, err := pg.GetPlanner()
+					if err != nil {
+						// If we fail to get the planner, we have to cancel the context
+						// to stop this and the other goroutines via ctxError.
+						cancelError(fmt.Errorf("failed to get a planner: %v", err))
+						return
+					}
+
 					outContent, opTimes, err := planner.PlanOperation(queryFilePath, cfg.OutputFormat)
 					res := QueryPlanResult{
 						FileName: queryFile.Name(),

router/pkg/plan_generator/plan_generator_test.go

@@ -407,3 +407,22 @@ func TestPlanGenerator(t *testing.T) {
 	})
 
 }
+
+func BenchmarkPlanGenerator(b *testing.B) {
+	tempDir := b.TempDir()
+	cfg := QueryPlanConfig{
+		SourceDir:       path.Join(getTestDataDir(), "queries", "bench"),
+		OutDir:          tempDir,
+		ExecutionConfig: path.Join(getTestDataDir(), "execution_config", "base.json"),
+		Timeout:         "30s",
+		Concurrency:     1,
+	}
+	b.ReportAllocs()
+	b.ResetTimer()
+	for b.Loop() {
+		err := PlanGenerator(context.Background(), cfg)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}

router/pkg/plan_generator/testdata/queries/bench/full.graphql

@@ -0,0 +1,125 @@
+query Full {
+  employees {
+    # resolved through employees subgraph
+    id
+    # overridden by the products subgraph
+    notes
+    details {
+      # resolved through either employees or family subgraph
+      forename
+      surname
+      # resolved through employees subgraph
+      location {
+        language
+      }
+      # resolved through family subgraph
+      hasChildren
+      # maritalStatus can return null
+      maritalStatus
+      nationality
+      # pets can return null
+      pets {
+        class
+        gender
+        name
+        ... on Cat {
+          type
+        }
+        ... on Dog {
+          breed
+        }
+        ... on Alligator {
+          dangerous
+        }
+      }
+    }
+    # resolved through employees subgraph
+    role {
+      departments
+      title
+      ... on Engineer {
+        engineerType
+      }
+      ... on Operator {
+        operatorType
+      }
+    }
+    # resolved through hobbies subgraph
+    hobbies {
+      ... on Exercise {
+        category
+      }
+      ... on Flying {
+        planeModels
+        yearsOfExperience
+      }
+      ... on Gaming {
+        genres
+        name
+        yearsOfExperience
+      }
+      ... on Other {
+        name
+      }
+      ... on Programming {
+        languages
+      }
+      ... on Travelling {
+        countriesLived {
+          language
+          key {
+            name
+          }
+        }
+      }
+    }
+    # resolved through products subgraph
+    products
+  }
+  # can return null
+  employee(id: 1) {
+    # resolved through employees subgraph
+    id
+    details {
+      forename
+      location {
+        language
+      }
+    }
+  }
+  teammates(team: OPERATIONS) {
+    # resolved through employees subgraph
+    id
+    ...EmployeeNameFragment
+    # resolved through products subgraph
+    products
+  }
+  productTypes {
+    ... on Documentation {
+      url(product: SDK)
+      urls(products: [COSMO, MARKETING])
+    }
+    ... on Consultancy {
+      lead {
+        ...EmployeeNameFragment
+      }
+      name
+    }
+  }
+  a: findEmployees(criteria: {
+    hasPets: true, nationality: UKRAINIAN, nested: { maritalStatus: ENGAGED }
+  }) {
+    ...EmployeeNameFragment
+  }
+  b: findEmployees(criteria: {
+    hasPets: true, nationality: GERMAN, nested: { maritalStatus: MARRIED, hasChildren: true }
+  }) {
+    ...EmployeeNameFragment
+  }
+}
+
+fragment EmployeeNameFragment on Employee {
+  details {
+    forename
+  }
+}