fix: Fixed vuln scanning

server/internal/services/findings.go

@@ -303,15 +303,33 @@ func ListFindings(ctx context.Context, instanceID, serverID string) ([]models.Vu
 func ApplyFindingDiff(ctx context.Context, instanceID, serverID string, d FindingDiff, now time.Time) error {
 	col := db.Col("vuln_findings")
 
+	// One BulkWrite per batch, not one UpdateOne per finding. A freshly scanned
+	// Ubuntu host opens tens of thousands of findings, and at one round trip each
+	// that is minutes of sequential latency during which the tick holds the
+	// leader and every other server waits its turn. Unordered, because the
+	// upserts are independent and one duplicate-key race must not abandon the
+	// rest of the batch.
+	const bulkBatch = 1000
+	ops := make([]mongo.WriteModel, 0, bulkBatch)
+
+	flush := func() error {
+		if len(ops) == 0 {
+			return nil
+		}
+		_, err := col.BulkWrite(ctx, ops, options.BulkWrite().SetOrdered(false))
+		ops = ops[:0]
+		return err
+	}
+
 	for _, f := range d.Upserts {
-		_, err := col.UpdateOne(ctx,
-			bson.M{
+		ops = append(ops, mongo.NewUpdateOneModel().
+			SetFilter(bson.M{
 				"instance_id":  instanceID,
 				"server_id":    serverID,
 				"cve_id":       f.CVEID,
 				"package_name": f.PackageName,
-			},
-			bson.M{
+			}).
+			SetUpdate(bson.M{
 				"$set": bson.M{
 					"installed_version": f.Installed,
 					"fixed_in":          f.FixedIn,
@@ -329,13 +347,18 @@ func ApplyFindingDiff(ctx context.Context, instanceID, serverID string, d Findin
 					"first_seen":   f.FirstSeen,
 				},
 				"$unset": bson.M{"fixed_at": "", "accepted": ""},
-			},
-			options.UpdateOne().SetUpsert(true),
-		)
-		if err != nil {
-			return err
+			}).
+			SetUpsert(true))
+
+		if len(ops) >= bulkBatch {
+			if err := flush(); err != nil {
+				return err
+			}
 		}
 	}
+	if err := flush(); err != nil {
+		return err
+	}
 
 	if len(d.FixedIDs) > 0 {
 		if _, err := col.UpdateMany(ctx,