Fetching Memcached Stats in Golang (Detailed Guide w/ Code Examples)

Use Case(s)

Memcached stats provide valuable information about the state of your cache. They can be used for:

1. Monitoring the performance and health of a Memcached server.
2. Diagnosing issues related to cache hit ratio, memory usage etc.
3. Fine tuning cache settings based on gathered statistics.

Code Examples

We use gomemcache, the Memcached client library for Go.

Example 1: Get basic stats

package main

import (
   "github.com/bradfitz/gomemcache/memcache"
   "fmt"
)

func main() {
   mc := memcache.New("localhost:11211") // connect to memcache server

   stats, err := mc.Stats() // get stats from server
   if err != nil {
       fmt.Println(err)
       return
   }

   fmt.Printf("%+v\n", stats) // print all stats
}

In this example, we first establish a connection to the Memcached server using its address (in this case, localhost on port 11211). We then fetch the stats using mc.Stats() and print them.

Example 2: Get specific stat

package main

import (
   "github.com/bradfitz/gomemcache/memcache"
   "fmt"
)

func main() {
   mc := memcache.New("localhost:11211") // connect to memcache server

   stats, err := mc.Stats() // get stats from server
   if err != nil {
       fmt.Println(err)
       return
   }

   fmt.Printf("Cache Hits: %s\n", stats["get_hits"]) // print cache hits stat
}

In this example, we fetch a specific stat (get_hits), providing the number of successful get commands.

Best Practices

1. Don't fetch stats excessively: Fetching stats too often can have a slight performance impact on the server. Do it only as needed.
2. Handle errors properly: Always check for errors when fetching stats. Any network hiccup or issue with Memcached can lead to errors.

Common Mistakes

Not checking for errors: When using mc.Stats(), an error can be returned for a variety of reasons (e.g., network issues, incorrect server address). Always handle these potential errors in your code.

FAQs

Q1: Can I get other stats like memory usage?

Yes, you can get any of the stats that Memcached provides such as total memory, used memory, hit ratios etc. The exact stat name is what you provide as the key to the stats dictionary.

Q2: How often should I fetch Memcached stats?

The answer depends on your specific use case. If you're debugging an issue or monitoring load on your cache, you might do it more frequently. In production systems, fetching every 5-10 minutes is pretty standard.