Tablet throttler: remove LowPriority logic (#16013)

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

go/vt/vttablet/tabletmanager/rpc_throttler.go

@@ -34,7 +34,6 @@ func (tm *TabletManager) CheckThrottler(ctx context.Context, req *tabletmanagerd
  req.AppName = throttlerapp.VitessName.String()
  }
  flags := &throttle.CheckFlags{
- LowPriority: false,
  SkipRequestHeartbeats: true,
  }
  checkResult := tm.QueryServiceControl.CheckThrottler(ctx, req.AppName, flags)

go/vt/vttablet/tabletserver/tabletserver.go

@@ -1896,7 +1896,6 @@ func (tsv *TabletServer) registerThrottlerCheckHandlers() {
  appName = throttlerapp.DefaultName.String()
  }
  flags := &throttle.CheckFlags{
- LowPriority: (r.URL.Query().Get("p") == "low"),
  SkipRequestHeartbeats: (r.URL.Query().Get("s") == "true"),
  }
  checkResult := tsv.lagThrottler.CheckByType(ctx, appName, remoteAddr, flags, checkType)

go/vt/vttablet/tabletserver/throttle/check.go

@@ -67,7 +67,6 @@ var (
 type CheckFlags struct {
  ReadCheck bool
  OverrideThreshold float64
- LowPriority bool
  OKIfNotExists bool
  SkipRequestHeartbeats bool
 }
@@ -91,14 +90,6 @@ func NewThrottlerCheck(throttler *Throttler) *ThrottlerCheck {
 func (check *ThrottlerCheck) checkAppMetricResult(ctx context.Context, appName string, storeType string, storeName string, metricResultFunc base.MetricResultFunc, flags *CheckFlags) (checkResult *CheckResult) {
  // Handle deprioritized app logic
  denyApp := false
- metricName := fmt.Sprintf("%s/%s", storeType, storeName)
- if flags.LowPriority {
- if _, exists := check.throttler.nonLowPriorityAppRequestsThrottled.Get(metricName); exists {
- // a non-deprioritized app, ie a "normal" app, has recently been throttled.
- // This is now a deprioritized app. Deny access to this request.
- denyApp = true
- }
- }
  //
  metricResult, threshold := check.throttler.AppRequestMetricResult(ctx, appName, metricResultFunc, denyApp)
  if flags.OverrideThreshold > 0 {
@@ -125,11 +116,6 @@ func (check *ThrottlerCheck) checkAppMetricResult(ctx context.Context, appName s
  // casual throttling
  statusCode = http.StatusTooManyRequests // 429
  err = base.ErrThresholdExceeded
-
- if !flags.LowPriority && !flags.ReadCheck && throttlerapp.VitessName.Equals(appName) {
- // low priority requests will henceforth be denied
- go check.throttler.nonLowPriorityAppRequestsThrottled.SetDefault(metricName, true)
- }
  default:
  // all good!
  statusCode = http.StatusOK // 200

go/vt/vttablet/tabletserver/throttle/client.go

@@ -56,30 +56,14 @@ type Client struct {
  lastSuccessfulThrottle int64
 }
 
-// NewProductionClient creates a client suitable for foreground/production jobs, which have normal priority.
-func NewProductionClient(throttler *Throttler, appName throttlerapp.Name, checkType ThrottleCheckType) *Client {
- initThrottleTicker()
- return &Client{
- throttler: throttler,
- appName: appName,
- checkType: checkType,
- flags: CheckFlags{
- LowPriority: false,
- },
- }
-}
-
-// NewBackgroundClient creates a client suitable for background jobs, which have low priority over production traffic,
-// e.g. migration, table pruning, vreplication
+// NewBackgroundClient creates a client
 func NewBackgroundClient(throttler *Throttler, appName throttlerapp.Name, checkType ThrottleCheckType) *Client {
  initThrottleTicker()
  return &Client{
  throttler: throttler,
  appName: appName,
  checkType: checkType,
- flags: CheckFlags{
- LowPriority: true,
- },
+ flags: CheckFlags{},
  }
 }
 

go/vt/vttablet/tabletserver/throttle/throttler.go

@@ -93,8 +93,6 @@ const (
  aggregatedMetricsExpiration = 5 * time.Second
  recentAppsExpiration = time.Hour * 24
 
- nonDeprioritizedAppMapExpiration = time.Second
-
  dormantPeriod = time.Minute // How long since last check to be considered dormant
  DefaultAppThrottleDuration = time.Hour
  DefaultThrottleRatio = 1.0
@@ -208,8 +206,7 @@ type Throttler struct {
 
  readSelfThrottleMetric func(context.Context, *mysql.Probe) *mysql.MySQLThrottleMetric // overwritten by unit test
 
- nonLowPriorityAppRequestsThrottled *cache.Cache
- httpClient *http.Client
+ httpClient *http.Client
 }
 
 // ThrottlerStatus published some status values from the throttler
@@ -256,7 +253,6 @@ func NewThrottler(env tabletenv.Env, srvTopoServer srvtopo.Server, ts *topo.Serv
  throttler.aggregatedMetrics = cache.New(aggregatedMetricsExpiration, 0)
  throttler.recentApps = cache.New(recentAppsExpiration, 0)
  throttler.metricsHealth = cache.New(cache.NoExpiration, 0)
- throttler.nonLowPriorityAppRequestsThrottled = cache.New(nonDeprioritizedAppMapExpiration, 0)
 
  throttler.httpClient = base.SetupHTTPClient(2 * mysqlCollectInterval)
  throttler.initThrottleTabletTypes()
@@ -728,7 +724,6 @@ func (throttler *Throttler) Operate(ctx context.Context, wg *sync.WaitGroup) {
  primaryStimulatorRateLimiter.Stop()
  throttler.aggregatedMetrics.Flush()
  throttler.recentApps.Flush()
- throttler.nonLowPriorityAppRequestsThrottled.Flush()
  wg.Done()
  }()
  // we do not flush throttler.throttledApps because this is data submitted by the user; the user expects the data to survive a disable+enable

go/vt/vttablet/tabletserver/throttle/throttler_test.go

@@ -157,7 +157,6 @@ func newTestThrottler() *Throttler {
  throttler.aggregatedMetrics = cache.New(10*aggregatedMetricsExpiration, 0)
  throttler.recentApps = cache.New(recentAppsExpiration, 0)
  throttler.metricsHealth = cache.New(cache.NoExpiration, 0)
- throttler.nonLowPriorityAppRequestsThrottled = cache.New(nonDeprioritizedAppMapExpiration, 0)
  throttler.metricsQuery.Store(metricsQuery)
  throttler.initThrottleTabletTypes()
  throttler.check = NewThrottlerCheck(throttler)