Bienvenue dans le quatrième volet de notre série sur la mise en œuvre d'un système sophistiqué de traitement des commandes ! Dans nos articles précédents, nous avons jeté les bases de notre projet, exploré les flux de travail temporels avancés et approfondi les opérations avancées de base de données. Aujourd'hui, nous nous concentrons sur un aspect tout aussi crucial de tout système prêt pour la production : la surveillance et les alertes.
Dans une architecture de microservices, en particulier celle qui gère des processus complexes tels que la gestion des commandes, une surveillance et des alertes efficaces sont cruciales. Ils nous permettent de :
Prometheus est une boîte à outils open source de surveillance et d'alerte des systèmes. Il est devenu un standard dans le monde du cloud natif en raison de ses fonctionnalités puissantes et de son vaste écosystème. Les composants clés incluent :
Nous utiliserons également Grafana, une plateforme open source populaire pour la surveillance et l'observabilité, pour créer des tableaux de bord et visualiser nos données Prometheus.
À la fin de cet article, vous pourrez :
Plongeons-nous !
Avant de commencer la mise en œuvre, passons en revue quelques concepts clés qui seront cruciaux pour notre configuration de surveillance et d'alerte.
L'observabilité fait référence à la capacité de comprendre l'état interne d'un système en examinant ses sorties. Dans les systèmes distribués comme notre système de traitement des commandes, l'observabilité englobe généralement trois piliers principaux :
Dans cet article, nous nous concentrerons principalement sur les métriques, mais nous aborderons la manière dont celles-ci peuvent être intégrées aux journaux et aux traces.
Prometheus suit une architecture basée sur le pull :
Prometheus propose quatre types de métriques de base :
PromQL（Prometheus Query Language）是一種用於查詢 Prometheus 資料的強大函數式語言。它允許您即時選擇和聚合時間序列資料。主要功能包括：
在建立儀表板和警報時，我們將看到 PromQL 查詢的範例。
Grafana 是一個多平台開源分析和互動式視覺化 Web 應用程式。當連接到受支援的資料來源（Prometheus 就是其中之一）時，它會為網路提供圖表、圖形和警報。主要功能包括：
現在我們已經介紹了這些概念，讓我們開始實施我們的監控和警報系統。
讓我們先設定 Prometheus 來監控我們的訂單處理系統。
首先，讓我們將 Prometheus 加入 docker-compose.yml 檔案：
services:
# ... other services ...
prometheus:
image: prom/prometheus:v2.30.3
volumes:
- ./prometheus:/etc/prometheus
- prometheus_data:/prometheus
command:
- '--config.file=/etc/prometheus/prometheus.yml'
- '--storage.tsdb.path=/prometheus'
- '--web.console.libraries=/usr/share/prometheus/console_libraries'
- '--web.console.templates=/usr/share/prometheus/consoles'
ports:
- 9090:9090
volumes:
# ... other volumes ...
prometheus_data: {}
接下來，在./prometheus目錄下建立prometheus.yml檔：
global:
scrape_interval: 15s
evaluation_interval: 15s
scrape_configs:
- job_name: 'prometheus'
static_configs:
- targets: ['localhost:9090']
- job_name: 'order_processing_api'
static_configs:
- targets: ['order_processing_api:8080']
- job_name: 'postgres'
static_configs:
- targets: ['postgres_exporter:9187']
此配置告訴 Prometheus 從自身、我們的訂單處理 API 和 Postgres 導出器（我們稍後將設定）中獲取指標。
為了公開 Go 服務的指標，我們將使用 Prometheus 用戶端程式庫。首先，將其添加到您的 go.mod 中：
go get github.com/prometheus/client_golang
現在，讓我們修改我們的主 Go 檔案以公開指標：
package main
import (
"net/http"
"github.com/gin-gonic/gin"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
var (
httpRequestsTotal = prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "http_requests_total",
Help: "Total number of HTTP requests",
},
[]string{"method", "endpoint", "status"},
)
httpRequestDuration = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "http_request_duration_seconds",
Help: "Duration of HTTP requests in seconds",
Buckets: prometheus.DefBuckets,
},
[]string{"method", "endpoint"},
)
)
func init() {
prometheus.MustRegister(httpRequestsTotal)
prometheus.MustRegister(httpRequestDuration)
}
func main() {
r := gin.Default()
// Middleware to record metrics
r.Use(func(c *gin.Context) {
timer := prometheus.NewTimer(httpRequestDuration.WithLabelValues(c.Request.Method, c.FullPath()))
c.Next()
timer.ObserveDuration()
httpRequestsTotal.WithLabelValues(c.Request.Method, c.FullPath(), string(c.Writer.Status())).Inc()
})
// Expose metrics endpoint
r.GET("/metrics", gin.WrapH(promhttp.Handler()))
// ... rest of your routes ...
r.Run(":8080")
}
此程式碼設定了兩個指標：
對於更動態的環境，Prometheus 支援各種服務發現機制。例如，如果您在 Kubernetes 上運行，則可以使用 Kubernetes SD 配置：
scrape_configs:
- job_name: 'kubernetes-pods'
kubernetes_sd_configs:
- role: pod
relabel_configs:
- source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape]
action: keep
regex: true
- source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_path]
action: replace
target_label: __metrics_path__
regex: (.+)
此配置將自動發現並從具有適當註解的 pod 中抓取指標。
Prometheus 將資料儲存在本機檔案系統上的時間序列資料庫中。您可以在 Prometheus 配置中配置保留時間和儲存大小：
global:
scrape_interval: 15s
evaluation_interval: 15s
storage:
tsdb:
retention.time: 15d
retention.size: 50GB
# ... rest of the configuration ...
此組態設定保留期為 15 天，最大儲存大小為 50GB。
在下一節中，我們將深入研究為訂單處理系統定義和實現自訂指標。
現在我們已經設定了 Prometheus 並實現了基本的 HTTP 指標，讓我們定義並實現特定於我們的訂單處理系統的自訂指標。
在設計指標時，重要的是要考慮我們希望從系統中獲得哪些見解。對於我們的訂單處理系統，我們可能想要追蹤：
讓我們實現這些指標：
package metrics
import (
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
var (
OrdersCreated = promauto.NewCounter(prometheus.CounterOpts{
Name: "orders_created_total",
Help: "The total number of created orders",
})
OrderProcessingTime = promauto.NewHistogram(prometheus.HistogramOpts{
Name: "order_processing_seconds",
Help: "Time taken to process an order",
Buckets: prometheus.LinearBuckets(0, 30, 10), // 0-300 seconds, 30-second buckets
})
OrderStatusGauge = promauto.NewGaugeVec(prometheus.GaugeOpts{
Name: "orders_by_status",
Help: "Number of orders by status",
}, []string{"status"})
PaymentProcessed = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "payments_processed_total",
Help: "The total number of processed payments",
}, []string{"status"})
InventoryUpdates = promauto.NewCounter(prometheus.CounterOpts{
Name: "inventory_updates_total",
Help: "The total number of inventory updates",
})
ShippingArrangementTime = promauto.NewHistogram(prometheus.HistogramOpts{
Name: "shipping_arrangement_seconds",
Help: "Time taken to arrange shipping",
Buckets: prometheus.LinearBuckets(0, 60, 5), // 0-300 seconds, 60-second buckets
})
)
現在我們已經定義了指標，讓我們在我們的服務中實現它們：
package main
import (
"time"
"github.com/yourusername/order-processing-system/metrics"
)
func createOrder(order Order) error {
startTime := time.Now()
// Order creation logic...
metrics.OrdersCreated.Inc()
metrics.OrderProcessingTime.Observe(time.Since(startTime).Seconds())
metrics.OrderStatusGauge.WithLabelValues("pending").Inc()
return nil
}
func processPayment(payment Payment) error {
// Payment processing logic...
if paymentSuccessful {
metrics.PaymentProcessed.WithLabelValues("success").Inc()
} else {
metrics.PaymentProcessed.WithLabelValues("failure").Inc()
}
return nil
}
func updateInventory(item Item) error {
// Inventory update logic...
metrics.InventoryUpdates.Inc()
return nil
}
func arrangeShipping(order Order) error {
startTime := time.Now()
// Shipping arrangement logic...
metrics.ShippingArrangementTime.Observe(time.Since(startTime).Seconds())
return nil
}
命名和標記指標時，請考慮以下最佳實踐：
For API endpoints, we’ve already implemented basic instrumentation. For database operations, we can add metrics like this:
func (s *Store) GetOrder(ctx context.Context, id int64) (Order, error) {
startTime := time.Now()
defer func() {
metrics.DBOperationDuration.WithLabelValues("GetOrder").Observe(time.Since(startTime).Seconds())
}()
// Existing GetOrder logic...
}
For Temporal workflows, we can add metrics in our activity implementations:
func ProcessOrderActivity(ctx context.Context, order Order) error {
startTime := time.Now()
defer func() {
metrics.WorkflowActivityDuration.WithLabelValues("ProcessOrder").Observe(time.Since(startTime).Seconds())
}()
// Existing ProcessOrder logic...
}
Now that we have our metrics set up, let’s visualize them using Grafana.
First, let’s add Grafana to our docker-compose.yml:
services:
# ... other services ...
grafana:
image: grafana/grafana:8.2.2
ports:
- 3000:3000
volumes:
- grafana_data:/var/lib/grafana
volumes:
# ... other volumes ...
grafana_data: {}
Let’s create a dashboard for our order processing system:
For our first panel, let’s create a graph of order creation rate:
Let’s add another panel for order processing time:
For order status distribution:
Continue adding panels for other metrics we’ve defined.
Grafana allows us to create variables that can be used across the dashboard. Let’s create a variable for time range:
Now we can use this in our queries like this: rate(orders_created_total[$time_range])
In the next section, we’ll set up alerting rules to notify us of potential issues in our system.
Now that we have our metrics and dashboards set up, let’s implement alerting to proactively notify us of potential issues in our system.
When designing alerts, consider the following principles:
For our order processing system, we might want to alert on:
Let’s create an alerts.yml file in our Prometheus configuration directory:
groups:
- name: order_processing_alerts
rules:
- alert: HighOrderProcessingErrorRate
expr: rate(order_processing_errors_total[5m]) / rate(orders_created_total[5m]) > 0.05
for: 5m
labels:
severity: critical
annotations:
summary: High order processing error rate
description: "Error rate is over the last 5 minutes"
- alert: SlowOrderProcessing
expr: histogram_quantile(0.95, rate(order_processing_seconds_bucket[5m])) > 300
for: 10m
labels:
severity: warning
annotations:
summary: Slow order processing
description: "95th percentile of order processing time is over the last 5 minutes"
- alert: UnusualOrderRate
expr: abs(rate(orders_created_total[1h]) - rate(orders_created_total[1h] offset 1d)) > (rate(orders_created_total[1h] offset 1d) * 0.3)
for: 30m
labels:
severity: warning
annotations:
summary: Unusual order creation rate
description: "Order creation rate has changed by more than 30% compared to the same time yesterday"
- alert: LowInventory
expr: inventory_level < 10
for: 5m
labels:
severity: warning
annotations:
summary: Low inventory level
description: "Inventory level for is "
- alert: HighPaymentFailureRate
expr: rate(payments_processed_total{status="failure"}[15m]) / rate(payments_processed_total[15m]) > 0.1
for: 15m
labels:
severity: critical
annotations:
summary: High payment failure rate
description: "Payment failure rate is over the last 15 minutes"
Update your prometheus.yml to include this alerts file:
rule_files: - "alerts.yml"
Now, let’s set up Alertmanager to handle our alerts. Add Alertmanager to your docker-compose.yml:
services:
# ... other services ...
alertmanager:
image: prom/alertmanager:v0.23.0
ports:
- 9093:9093
volumes:
- ./alertmanager:/etc/alertmanager
command:
- '--config.file=/etc/alertmanager/alertmanager.yml'
Create an alertmanager.yml in the ./alertmanager directory:
route:
group_by: ['alertname']
group_wait: 30s
group_interval: 5m
repeat_interval: 1h
receiver: 'email-notifications'
receivers:
- name: 'email-notifications'
email_configs:
- to: 'team@example.com'
from: 'alertmanager@example.com'
smarthost: 'smtp.example.com:587'
auth_username: 'alertmanager@example.com'
auth_identity: 'alertmanager@example.com'
auth_password: 'password'
Update your prometheus.yml to point to Alertmanager:
alerting:
alertmanagers:
- static_configs:
- targets:
- alertmanager:9093
In the Alertmanager configuration above, we’ve set up email notifications. You can also configure other channels like Slack, PagerDuty, or custom webhooks.
In our alerts, we’ve used severity labels. We can use these in Alertmanager to implement different routing or notification strategies based on severity:
route:
group_by: ['alertname']
group_wait: 30s
group_interval: 5m
repeat_interval: 1h
receiver: 'email-notifications'
routes:
- match:
severity: critical
receiver: 'pagerduty-critical'
- match:
severity: warning
receiver: 'slack-warnings'
receivers:
- name: 'email-notifications'
email_configs:
- to: 'team@example.com'
- name: 'pagerduty-critical'
pagerduty_configs:
- service_key: '<your-pagerduty-service-key>'
- name: 'slack-warnings'
slack_configs:
- api_url: '<your-slack-webhook-url>'
channel: '#alerts'
Monitoring database performance is crucial for maintaining a responsive and reliable system. Let’s set up monitoring for our PostgreSQL database.
First, add the Postgres exporter to your docker-compose.yml:
services:
# ... other services ...
postgres_exporter:
image: wrouesnel/postgres_exporter:latest
environment:
DATA_SOURCE_NAME: "postgresql://user:password@postgres:5432/dbname?sslmode=disable"
ports:
- 9187:9187
Make sure to replace user, password, and dbname with your actual PostgreSQL credentials.
Some important PostgreSQL metrics to monitor include:
Let’s create a new dashboard for database performance:
Let’s add some database-specific alerts to our alerts.yml:
- alert: HighDatabaseConnections
expr: pg_stat_activity_count > 100
for: 5m
labels:
severity: warning
annotations:
summary: High number of database connections
description: "There are active database connections"
- alert: LowCacheHitRatio
expr: pg_stat_database_blks_hit / (pg_stat_database_blks_hit + pg_stat_database_blks_read) < 0.9
for: 15m
labels:
severity: warning
annotations:
summary: Low database cache hit ratio
description: "Cache hit ratio is "
Monitoring Temporal workflows is essential for ensuring the reliability and performance of our order processing system.
Temporal provides a metrics client that we can use to expose metrics to Prometheus. Let’s update our Temporal worker to include metrics:
import (
"go.temporal.io/sdk/client"
"go.temporal.io/sdk/worker"
"go.temporal.io/sdk/contrib/prometheus"
)
func main() {
// ... other setup ...
// Create Prometheus metrics handler
metricsHandler := prometheus.NewPrometheusMetricsHandler()
// Create Temporal client with metrics
c, err := client.NewClient(client.Options{
MetricsHandler: metricsHandler,
})
if err != nil {
log.Fatalln("Unable to create Temporal client", err)
}
defer c.Close()
// Create worker with metrics
w := worker.New(c, "order-processing-task-queue", worker.Options{
MetricsHandler: metricsHandler,
})
// ... register workflows and activities ...
// Run the worker
err = w.Run(worker.InterruptCh())
if err != nil {
log.Fatalln("Unable to start worker", err)
}
}
Important Temporal metrics to monitor include:
Let’s create a dashboard for Temporal workflows:
Let’s add some Temporal-specific alerts to our alerts.yml:
- alert: HighWorkflowFailureRate
expr: rate(temporal_workflow_failed_total[15m]) / rate(temporal_workflow_completed_total[15m]) > 0.05
for: 15m
labels:
severity: critical
annotations:
summary: High workflow failure rate
description: "Workflow failure rate is over the last 15 minutes"
- alert: LongRunningWorkflow
expr: histogram_quantile(0.95, rate(temporal_workflow_execution_time_bucket[1h])) > 3600
for: 30m
labels:
severity: warning
annotations:
summary: Long-running workflows detected
description: "95th percentile of workflow execution time is over 1 hour"
These alerts will help you detect issues with your Temporal workflows, such as high failure rates or unexpectedly long-running workflows.
In the next sections, we’ll cover some advanced Prometheus techniques and discuss testing and validation of our monitoring setup.
As our monitoring system grows more complex, we can leverage some advanced Prometheus techniques to improve its efficiency and capabilities.
Recording rules allow you to precompute frequently needed or computationally expensive expressions and save their result as a new set of time series. This can significantly speed up the evaluation of dashboards and alerts.
Let’s add some recording rules to our Prometheus configuration. Create a rules.yml file:
groups:
- name: example_recording_rules
interval: 5m
rules:
- record: job:order_processing_rate:5m
expr: rate(orders_created_total[5m])
- record: job:order_processing_error_rate:5m
expr: rate(order_processing_errors_total[5m]) / rate(orders_created_total[5m])
- record: job:payment_success_rate:5m
expr: rate(payments_processed_total{status="success"}[5m]) / rate(payments_processed_total[5m])
Add this file to your Prometheus configuration:
rule_files: - "alerts.yml" - "rules.yml"
Now you can use these precomputed metrics in your dashboards and alerts, which can be especially helpful for complex queries that you use frequently.
The Pushgateway allows you to push metrics from jobs that can’t be scraped, such as batch jobs or serverless functions. Let’s add a Pushgateway to our docker-compose.yml:
services:
# ... other services ...
pushgateway:
image: prom/pushgateway
ports:
- 9091:9091
Now, you can push metrics to the Pushgateway from your batch jobs or short-lived processes. Here’s an example using the Go client:
import (
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/push"
)
func runBatchJob() {
// Define a counter for the batch job
batchJobCounter := prometheus.NewCounter(prometheus.CounterOpts{
Name: "batch_job_processed_total",
Help: "Total number of items processed by the batch job",
})
// Run your batch job and update the counter
// ...
// Push the metric to the Pushgateway
pusher := push.New("http://pushgateway:9091", "batch_job")
pusher.Collector(batchJobCounter)
if err := pusher.Push(); err != nil {
log.Printf("Could not push to Pushgateway: %v", err)
}
}
Don’t forget to add the Pushgateway as a target in your Prometheus configuration:
scrape_configs:
# ... other configs ...
- job_name: 'pushgateway'
static_configs:
- targets: ['pushgateway:9091']
For large-scale systems, you might need to set up Prometheus federation, where one Prometheus server scrapes data from other Prometheus servers. This allows you to aggregate metrics from multiple Prometheus instances.
Here’s an example configuration for a federated Prometheus setup:
scrape_configs:
- job_name: 'federate'
scrape_interval: 15s
honor_labels: true
metrics_path: '/federate'
params:
'match[]':
- '{job="order_processing_api"}'
- '{job="postgres_exporter"}'
static_configs:
- targets:
- 'prometheus-1:9090'
- 'prometheus-2:9090'
This configuration allows a higher-level Prometheus server to scrape specific metrics from other Prometheus servers.
Exemplars allow you to link metrics to trace data, providing a way to drill down from a high-level metric to a specific trace. This is particularly useful when integrating Prometheus with distributed tracing systems like Jaeger or Zipkin.
To use exemplars, you need to enable them in your Prometheus configuration:
global:
scrape_interval: 15s
evaluation_interval: 15s
exemplar_storage:
enable: true
Then, when instrumenting your code, you can add exemplars to your metrics:
import (
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
var (
orderProcessingDuration = promauto.NewHistogramVec(
prometheus.HistogramOpts{
Name: "order_processing_duration_seconds",
Help: "Duration of order processing in seconds",
Buckets: prometheus.DefBuckets,
},
[]string{"status"},
)
)
func processOrder(order Order) {
start := time.Now()
// Process the order...
duration := time.Since(start)
orderProcessingDuration.WithLabelValues(order.Status).Observe(duration.Seconds(),
prometheus.Labels{
"traceID": getCurrentTraceID(),
},
)
}
This allows you to link from a spike in order processing duration directly to the trace of a slow order, greatly aiding in debugging and performance analysis.
Ensuring the reliability of your monitoring system is crucial. Let’s explore some strategies for testing and validating our Prometheus setup.
When unit testing your Go code, you can use the prometheus/testutil package to verify that your metrics are being updated correctly:
import (
"testing"
"github.com/prometheus/client_golang/prometheus/testutil"
)
func TestOrderProcessing(t *testing.T) {
// Process an order
processOrder(Order{ID: 1, Status: "completed"})
// Check if the metric was updated
expected := `
# HELP order_processing_duration_seconds Duration of order processing in seconds
# TYPE order_processing_duration_seconds histogram
order_processing_duration_seconds_bucket{status="completed",le="0.005"} 1
order_processing_duration_seconds_bucket{status="completed",le="0.01"} 1
# ... other buckets ...
order_processing_duration_seconds_sum{status="completed"} 0.001
order_processing_duration_seconds_count{status="completed"} 1
`
if err := testutil.CollectAndCompare(orderProcessingDuration, strings.NewReader(expected)); err != nil {
t.Errorf("unexpected collecting result:\n%s", err)
}
}
To test that Prometheus is correctly scraping your metrics, you can set up an integration test that starts your application, waits for Prometheus to scrape it, and then queries Prometheus to verify the metrics:
func TestPrometheusIntegration(t *testing.T) {
// Start your application
go startApp()
// Wait for Prometheus to scrape (adjust the sleep time as needed)
time.Sleep(30 * time.Second)
// Query Prometheus
client, err := api.NewClient(api.Config{
Address: "http://localhost:9090",
})
if err != nil {
t.Fatalf("Error creating client: %v", err)
}
v1api := v1.NewAPI(client)
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
result, warnings, err := v1api.Query(ctx, "order_processing_duration_seconds_count", time.Now())
if err != nil {
t.Fatalf("Error querying Prometheus: %v", err)
}
if len(warnings) > 0 {
t.Logf("Warnings: %v", warnings)
}
// Check the result
if result.(model.Vector).Len() == 0 {
t.Errorf("Expected non-empty result")
}
}
It’s important to verify that your monitoring system performs well under load. You can use tools like hey or vegeta to generate load on your system while observing your metrics:
hey -n 10000 -c 100 http://localhost:8080/orders
While the load test is running, observe your Grafana dashboards and check that your metrics are updating as expected and that Prometheus is able to keep up with the increased load.
To test your alerting rules, you can temporarily adjust the thresholds to trigger alerts, or use Prometheus’s API to manually fire alerts:
curl -H "Content-Type: application/json" -d '{
"alerts": [
{
"labels": {
"alertname": "HighOrderProcessingErrorRate",
"severity": "critical"
},
"annotations": {
"summary": "High order processing error rate"
}
}
]
}' http://localhost:9093/api/v1/alerts
This will send a test alert to your Alertmanager, allowing you to verify that your notification channels are working correctly.
As you implement and scale your monitoring system, keep these challenges and considerations in mind:
High cardinality can lead to performance issues in Prometheus. Be cautious when adding labels to metrics, especially labels with many possible values (like user IDs or IP addresses). Instead, consider using histogram metrics or reducing the cardinality by grouping similar values.
For large-scale systems, consider:
Your monitoring system is critical infrastructure. Consider:
確保：
減少警報噪音：
在這篇文章中，我們介紹了使用 Prometheus 和 Grafana 對訂單處理系統進行全面監控和警報。我們設定了自訂指標，創建了資訊豐富的儀表板，實施了警報，並探索了先進的技術和注意事項。
在我們系列的下一部分中，我們將專注於分散式追蹤和日誌記錄。我們將介紹：
請繼續關注我們繼續增強我們的訂單處理系統，接下來的重點是更深入地了解我們的分散式系統的行為和性能！
您是否面臨著具有挑戰性的問題，或需要外部視角來看待新想法或專案？我可以幫忙！無論您是想在進行更大投資之前建立技術概念驗證，還是需要解決困難問題的指導，我都會為您提供協助。
如果您有興趣與我合作，請透過電子郵件與我聯繫：hungaikevin@gmail.com。
讓我們將挑戰轉化為機會！
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