Context deadline exceeded.md

When a context is canceled or its deadline is exceeded, all operations associated with that context are terminated, and the corresponding functions return with an error. The error message "context deadline exceeded" indicates that the operation took longer than the deadline specified in the context.

In the example below, a context with a deadline of 2 seconds is created using context.WithTimeout. However, the performOperation function intentionally simulates a long-running operation that takes 3 seconds to complete. As a result, when the operation is executed with the context, the context deadline exceeded error is returned.

package main

import (
	"context"
	"fmt"
	"time"
)

func main() {
	// Create a context with a deadline of 2 seconds.
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()

	// Simulate a long-running operation that takes more than 2 seconds.
	time.Sleep(3 * time.Second)

	// Perform some operation with the context.
	if err := performOperation(ctx); err != nil {
		fmt.Println("Error:", err)
	}
}

func performOperation(ctx context.Context) error {
	select {
	case <-ctx.Done():
		// The context deadline has been exceeded.
		return ctx.Err()
	default:
		// Perform the operation
		fmt.Println("Operation completed successfully")
		return nil
	}
}

Solutions:

Before being able to solve the problem, you need to determine what is actually failing.

• Investigate Network connectivity
  • Can required systems communicate in general? Are there any firewalls in place that can be preventing communication? If in the cloud, are the instances in the same VPC/Network? Do the instances belong to the correct/expected Security Groups?
• Resource Contention
  • Are we asking too much of the underlying provisioned infrastructure? What is our CPU/Memory usage?
• Slow I/O
  • Are we using an external storage backend? Are we seeing I/O wait? Are we in the cloud? Do we have enough IOPS provisioned for our storage?