Verbosity in Java Memcached (Detailed Guide w/ Code Examples)

Use Case(s)

Verbosity controls the amount of output that Memcached will send for certain commands. In a Java environment, verbosity can be used in the following scenarios:

1. Debugging and monitoring - increasing verbosity will provide more detailed logs, making it easier to troubleshoot issues.
2. Performance tuning - the additional information can help identify bottlenecks or inefficiencies.

Code Examples

For interacting with Memcached from a Java application, we usually use libraries such as "spymemcached" or "Xmemcached". Here's an example of how you might control verbosity using spymemcached:

// Import necessary classes
import net.spy.memcached.MemcachedClient;
import java.net.InetSocketAddress;

public class Main {
  public static void main(String[] args) {
    try {
      // Create a connection to memcached server on localhost port 11211 
      MemcachedClient mc = new MemcachedClient(new InetSocketAddress("localhost", 11211));

      // Use the raw command interface to send the verbosity command
      mc.getConnector().getAsciiProcessor().processOperation(mc
          .createRawTextOp(null, "verbosity 3"), null);
      
      // Insert code here that interacts with Memcached. The server should now output more details for each operation
      
    } catch(Exception ex) {
      System.err.println( "Exception caught: " + ex.toString() );
    }
  }
}

This code establishes a connection to a Memcached server running on localhost and sends a "verbosity" command to increase the verbosity level.

Best Practices

• Only use high verbosity levels during debugging sessions, as it could have a performance impact.
• Always ensure proper error handling when operating at a high verbosity level, as it might present more error scenarios.
• It's usually a good idea to encapsulate Memcached operations within a dedicated service or DAO in your Java code, to keep control over the verbosity and other settings in one place.

Common Mistakes

• Increasing verbosity without understanding its impact: High verbosity levels can slow down your system due to excessive logging.
• Not resetting verbosity level back to default after debugging.

FAQs

Q: Does changing verbosity affect the performance of Memcached? A: Yes. A higher verbosity level means more CPU spent on generating log messages. Thus, it is better to use it for debugging purposes, and not in production environments.

Q: Can I set the verbosity level permanently? A: No. The verbosity level resets when the server restarts. To set the verbosity each time Memcached starts, you will need to include it in your start command or script.