Tablet throttler: read and use MySQL host metrics (vitessio#16904)

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>
Signed-off-by: Renan Rangel <rrangel@slack-corp.com>

Author: shlomi-noach

go/osutil/loadavg.go

@@ -0,0 +1,33 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package osutil
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// parseLoadAvg parses the load average from the content of /proc/loadavg or sysctl output.
+// Input such as "1.00 0.99 0.98 1/1 1", "2.83 3.01 3.36"
+func parseLoadAvg(content string) (float64, error) {
+	fields := strings.Fields(content)
+	if len(fields) == 0 {
+		return 0, fmt.Errorf("unexpected loadavg content: %s", content)
+	}
+	return strconv.ParseFloat(fields[0], 64)
+}

go/osutil/loadavg_darwin.go

@@ -0,0 +1,40 @@
+//go:build darwin
+
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package osutil
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+// LoadAvg returns the past 1 minute system load average. This works on linux and darwin systems.
+// On other systems, it returns 0 with no error.
+func LoadAvg() (float64, error) {
+	cmd := exec.Command("sysctl", "-n", "vm.loadavg")
+	// Sample output: `{ 2.83 3.01 3.36 }`
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return 0, err
+	}
+	if len(output) < 1 {
+		return 0, fmt.Errorf("unexpected sysctl output: %q", output)
+	}
+	output = output[1:] // Remove the leading `{ `
+	return parseLoadAvg(string(output))
+}

go/osutil/loadavg_linux.go

@@ -0,0 +1,33 @@
+//go:build linux
+
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package osutil
+
+import (
+	"os"
+)
+
+// LoadAvg returns the past 1 minute system load average. This works on linux and darwin systems.
+// On other systems, it returns 0 with no error.
+func LoadAvg() (float64, error) {
+	content, err := os.ReadFile("/proc/loadavg")
+	if err != nil {
+		return 0, err
+	}
+	return parseLoadAvg(string(content))
+}

go/osutil/loadavg_other.go

@@ -0,0 +1,25 @@
+//go:build !linux && !darwin
+
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package osutil
+
+// LoadAvg returns the past 1 minute system load average. This works on linux and darwin systems.
+// On other systems, it returns 0 with no error.
+func LoadAvg() (float64, error) {
+	return 0, nil
+}

go/osutil/loadavg_test.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package osutil
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLoadAvgValue(t *testing.T) {
+	tcases := []struct {
+		input   string
+		loadavg float64
+		isError bool
+	}{
+		{
+			input:   "",
+			isError: true,
+		},
+		{
+			input:   "{}",
+			isError: true,
+		},
+		{
+			input:   "{ x y z }",
+			isError: true,
+		},
+		{
+			input:   "1",
+			loadavg: 1.0,
+		},
+		{
+			input:   "0.00 0.00 0.00 1/1 1",
+			loadavg: 0.0,
+		},
+		{
+			input:   "2.72 2.89 3.17",
+			loadavg: 2.72,
+		},
+		{
+			input:   "   2.72 2.89 3.17",
+			loadavg: 2.72,
+		},
+	}
+	for _, tcase := range tcases {
+		t.Run(tcase.input, func(t *testing.T) {
+			loadavg, err := parseLoadAvg(tcase.input)
+			if tcase.isError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tcase.loadavg, loadavg)
+			}
+		})
+	}
+}
+
+func TestLoadAvg(t *testing.T) {
+	loadavg, err := LoadAvg()
+	assert.NoError(t, err)
+	assert.GreaterOrEqual(t, loadavg, 0.0)
+}

go/test/endtoend/tabletmanager/throttler_topo/throttler_test.go

@@ -215,7 +215,7 @@ func warmUpHeartbeat(t *testing.T) tabletmanagerdatapb.CheckThrottlerResponseCod
 }
 
 // waitForThrottleCheckStatus waits for the tablet to return the provided HTTP code in a throttle check
-func waitForThrottleCheckStatus(t *testing.T, tablet *cluster.Vttablet, wantCode tabletmanagerdatapb.CheckThrottlerResponseCode) bool {
+func waitForThrottleCheckStatus(t *testing.T, tablet *cluster.Vttablet, wantCode tabletmanagerdatapb.CheckThrottlerResponseCode) (*tabletmanagerdatapb.CheckThrottlerResponse, bool) {
 	_ = warmUpHeartbeat(t)
 	ctx, cancel := context.WithTimeout(context.Background(), onDemandHeartbeatDuration*4)
 	defer cancel()
@@ -229,11 +229,11 @@ func waitForThrottleCheckStatus(t *testing.T, tablet *cluster.Vttablet, wantCode
 		if wantCode == resp.Check.ResponseCode {
 			// Wait for any cached check values to be cleared and the new
 			// status value to be in effect everywhere before returning.
-			return true
+			return resp.Check, true
 		}
 		select {
 		case <-ctx.Done():
-			return assert.EqualValues(t, wantCode, resp.Check.StatusCode, "response: %+v", resp)
+			return resp.Check, false
 		case <-ticker.C:
 		}
 	}
@@ -779,16 +779,16 @@ func TestUpdateAppCheckedMetrics(t *testing.T) {
 		}
 		waitForThrottleCheckStatus(t, primaryTablet, tabletmanagerdatapb.CheckThrottlerResponseCode_THRESHOLD_EXCEEDED)
 	})
-	t.Run("assigning 'loadavg' metrics to 'test' app", func(t *testing.T) {
+	t.Run("assigning 'threads_running' metrics to 'test' app", func(t *testing.T) {
 		{
-			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: "loadavg", Threshold: 7777}
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: base.ThreadsRunningMetricName.String(), Threshold: 7777}
 			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, nil)
 			assert.NoError(t, err)
 		}
 		{
 			req := &vtctldatapb.UpdateThrottlerConfigRequest{}
 			appCheckedMetrics := map[string]*topodatapb.ThrottlerConfig_MetricNames{
-				testAppName.String(): {Names: []string{"loadavg"}},
+				testAppName.String(): {Names: []string{base.ThreadsRunningMetricName.String()}},
 			}
 			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, appCheckedMetrics)
 			assert.NoError(t, err)
@@ -802,18 +802,18 @@ func TestUpdateAppCheckedMetrics(t *testing.T) {
 		for _, tablet := range []cluster.Vttablet{*primaryTablet, *replicaTablet} {
 			throttler.WaitForThrottlerStatusEnabled(t, &clusterInstance.VtctldClientProcess, &tablet, true, &throttler.Config{Query: throttler.DefaultQuery, Threshold: unreasonablyLowThreshold.Seconds()}, throttlerEnabledTimeout)
 		}
-		t.Run("validating OK response from throttler since it's checking loadavg", func(t *testing.T) {
-			if !waitForThrottleCheckStatus(t, primaryTablet, tabletmanagerdatapb.CheckThrottlerResponseCode_OK) {
+		t.Run("validating OK response from throttler since it's checking threads_running", func(t *testing.T) {
+			if _, ok := waitForThrottleCheckStatus(t, primaryTablet, tabletmanagerdatapb.CheckThrottlerResponseCode_OK); !ok {
 				t.Logf("throttler primary status: %+v", throttleStatus(t, primaryTablet))
 				t.Logf("throttler replica status: %+v", throttleStatus(t, replicaTablet))
 			}
 		})
 	})
-	t.Run("assigning 'loadavg,lag' metrics to 'test' app", func(t *testing.T) {
+	t.Run("assigning 'threads_running,lag' metrics to 'test' app", func(t *testing.T) {
 		{
 			req := &vtctldatapb.UpdateThrottlerConfigRequest{}
 			appCheckedMetrics := map[string]*topodatapb.ThrottlerConfig_MetricNames{
-				testAppName.String(): {Names: []string{"loadavg,lag"}},
+				testAppName.String(): {Names: []string{base.ThreadsRunningMetricName.String(), base.LagMetricName.String()}},
 			}
 			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, appCheckedMetrics)
 			assert.NoError(t, err)
@@ -831,9 +831,51 @@ func TestUpdateAppCheckedMetrics(t *testing.T) {
 			waitForThrottleCheckStatus(t, primaryTablet, tabletmanagerdatapb.CheckThrottlerResponseCode_THRESHOLD_EXCEEDED)
 		})
 	})
+	t.Run("assigning 'mysqld-loadavg,mysqld-datadir-used-ratio' metrics to 'test' app", func(t *testing.T) {
+		{
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: base.MysqldDatadirUsedRatioMetricName.String(), Threshold: 0.9999}
+			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, nil)
+			assert.NoError(t, err)
+		}
+		{
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: base.MysqldLoadAvgMetricName.String(), Threshold: 5555}
+			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, nil)
+			assert.NoError(t, err)
+		}
+		{
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{}
+			appCheckedMetrics := map[string]*topodatapb.ThrottlerConfig_MetricNames{
+				testAppName.String(): {Names: []string{base.MysqldDatadirUsedRatioMetricName.String(), base.MysqldLoadAvgMetricName.String()}},
+			}
+			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, appCheckedMetrics)
+			assert.NoError(t, err)
+		}
+		{
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{Threshold: extremelyHighThreshold.Seconds()}
+			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, nil)
+			assert.NoError(t, err)
+		}
+		// Wait for the throttler to be enabled everywhere with new config.
+		for _, tablet := range []cluster.Vttablet{*primaryTablet, *replicaTablet} {
+			throttler.WaitForThrottlerStatusEnabled(t, &clusterInstance.VtctldClientProcess, &tablet, true, &throttler.Config{Query: throttler.DefaultQuery, Threshold: extremelyHighThreshold.Seconds()}, throttlerEnabledTimeout)
+		}
+		t.Run("validating OK response from throttler since it's checking mysqld-loadavg,mysqld-datadir-used-ratio", func(t *testing.T) {
+			resp, ok := waitForThrottleCheckStatus(t, primaryTablet, tabletmanagerdatapb.CheckThrottlerResponseCode_OK)
+			if !ok {
+				t.Logf("response: %+v", resp)
+				t.Logf("throttler primary status: %+v", throttleStatus(t, primaryTablet))
+				t.Logf("throttler replica status: %+v", throttleStatus(t, replicaTablet))
+			}
+			require.Contains(t, resp.Metrics, base.MysqldDatadirUsedRatioMetricName.String())
+			require.Contains(t, resp.Metrics, base.MysqldLoadAvgMetricName.String())
+			assert.NotContains(t, resp.Metrics, base.ThreadsRunningMetricName.String())
+
+			assert.NotZero(t, resp.Metrics[base.MysqldDatadirUsedRatioMetricName.String()].Value)
+		})
+	})
 	t.Run("removing assignment from 'test' app and restoring defaults", func(t *testing.T) {
 		{
-			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: "loadavg", Threshold: 0}
+			req := &vtctldatapb.UpdateThrottlerConfigRequest{MetricName: base.ThreadsRunningMetricName.String(), Threshold: 0}
 			_, err := throttler.UpdateThrottlerTopoConfig(clusterInstance, req, nil, nil)
 			assert.NoError(t, err)
 		}

go/test/endtoend/throttler/util.go

@@ -529,7 +529,7 @@ func WaitForValidData(t *testing.T, tablet *cluster.Vttablet, timeout time.Durat
 	selfCheckURL := fmt.Sprintf("http://localhost:%d/throttler/check-self", tablet.HTTPPort)
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
 	defer cancel()
-	ticker := time.NewTicker(500 * time.Millisecond)
+	ticker := time.NewTicker(time.Second)
 	defer ticker.Stop()
 
 	for {
@@ -548,8 +548,10 @@ func WaitForValidData(t *testing.T, tablet *cluster.Vttablet, timeout time.Durat
 		}
 		select {
 		case <-ctx.Done():
-			t.Errorf("timed out waiting for %s tablet's throttler to return a valid result after %v; last seen value: %+v",
-				tablet.Alias, timeout, checkResp)
+			respByte, _ := io.ReadAll(checkResp.Body)
+			body := string(respByte)
+			require.Failf(t, "time out", "waiting for %s tablet's throttler to return a valid result after %v; last seen result: %+v",
+				tablet.Alias, timeout, body)
 			return
 		case <-ticker.C:
 		}

go/textutil/strings.go

@@ -90,6 +90,19 @@ func SingleWordCamel(w string) string {
 	return strings.ToUpper(w[0:1]) + strings.ToLower(w[1:])
 }
 
+var multiWordSplitterRegexp = regexp.MustCompile(`[-_.\s]+`)
+
+// PascalCase turns a string into PascalCase by splitting it into words and
+// capitalizing the first letter of each word.
+func PascalCase(w string) string {
+	var b strings.Builder
+	words := multiWordSplitterRegexp.Split(w, -1)
+	for _, word := range words {
+		b.WriteString(SingleWordCamel(word))
+	}
+	return b.String()
+}
+
 // ValueIsSimulatedNull returns true if the slice value represents
 // a NULL or unknown/unspecified value. This is used to distinguish
 // between a zero value empty slice and a user provided value of an