diagnostic settings scanner max concurrent requests are set to 200. A…

…lso removed the use of WaitGroups

internal/aprl_scanner.go

@@ -11,7 +11,6 @@ import (
 	"io/fs"
 	"math"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/Azure/azqr/internal/azqr"
@@ -128,14 +127,7 @@ func (sc AprlScanner) Scan(ctx context.Context, cred azcore.TokenCredential, ser
 
 	batches := int(math.Ceil(float64(len(rules)) / 12))
 
-	var wg sync.WaitGroup
 	ch := make(chan []azqr.AprlResult, 12)
-	wg.Add(batches)
-
-	go func() {
-		wg.Wait()
-		close(ch)
-	}()
 
 	batchSzie := 12
 	batchNumber := 0
@@ -146,7 +138,6 @@ func (sc AprlScanner) Scan(ctx context.Context, cred azcore.TokenCredential, ser
 		}
 
 		go func(r []azqr.AprlRecommendation, b int) {
-			defer wg.Done()
 			if b > 0 {
 				// Staggering queries to avoid throttling. Max 15 queries each 5 seconds.
 				// https://learn.microsoft.com/en-us/azure/governance/resource-graph/concepts/guidance-for-throttled-requests#staggering-queries

internal/scanner.go

@@ -7,7 +7,6 @@ import (
 	"context"
 	"fmt"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/Azure/azqr/internal/azqr"
@@ -169,14 +168,7 @@ func (sc Scanner) Scan(params *ScanParams) {
 			}
 
 			// scan each resource group
-			var wg sync.WaitGroup
 			ch := make(chan []azqr.AzqrServiceResult, 5)
-			wg.Add(len(params.ServiceScanners))
-
-			go func() {
-				wg.Wait()
-				close(ch)
-			}()
 
 			for _, s := range params.ServiceScanners {
 				err := s.Init(config)
@@ -185,8 +177,6 @@ func (sc Scanner) Scan(params *ScanParams) {
 				}
 
 				go func(s azqr.IAzureScanner) {
-					defer wg.Done()
-
 					res, err := sc.retry(3, 10*time.Millisecond, s, &scanContext)
 					if err != nil {
 						cancel()

internal/scanners/diagnostics_settings.go

@@ -8,7 +8,6 @@ import (
 	"math"
 	"net/http"
 	"strings"
-	"sync"
 
 	"github.com/Azure/azqr/internal/azqr"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
@@ -41,14 +40,10 @@ func (d *DiagnosticSettingsScanner) ListResourcesWithDiagnosticSettings(resource
 
 	batches := int(math.Ceil(float64(len(resources)) / 20))
 
-	var wg sync.WaitGroup
 	ch := make(chan map[string]bool, 5)
-	wg.Add(batches)
 
-	go func() {
-		wg.Wait()
-		close(ch)
-	}()
+	maxConcurrency := 200 // max number of concurrent requests
+	limiter := make(chan struct{}, maxConcurrency)
 
 	azqr.LogResourceTypeScan("Diagnostic Settings")
 
@@ -59,8 +54,9 @@ func (d *DiagnosticSettingsScanner) ListResourcesWithDiagnosticSettings(resource
 		if j > len(resources) {
 			j = len(resources)
 		}
+		limiter <- struct{}{} // Acquire a token. Waits here for token releases from the limiter. 
 		go func(r []*string) {
-			defer wg.Done()
+			defer func() { <-limiter }() // Release the token
 			resp, err := d.restCall(d.ctx, r)
 			if err != nil {
 				log.Fatal().Err(err).Msg("Failed to get diagnostic settings")