Getting Memory Stats in PHP Redis (Detailed Guide w/ Code Examples)

Use Case(s)

In PHP, you might need to retrieve memory statistics from a Redis instance for monitoring, debugging, or performance tuning. This is particularly useful for identifying memory leaks or excessive memory usage.

Code Examples

Here's how you can get memory stats with the PHPRedis extension:

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);
$info = $redis->info();
echo 'Used memory: ', $info['used_memory'];

The info() method returns an array of various server stats including memory details. The used_memory key in that array gives the total number of bytes allocated by Redis using its allocator.

Best Practices

Consider fetching memory stats at regular intervals or during low traffic times, as this operation may have a slight impact on the performance due to the information gathering process.

Common Mistakes

A common mistake is to overlook that memory stats will vary greatly depending on your Redis configuration and data structures used. Therefore it’s critical to interpret these numbers in light of your specific use case rather than comparing them to typical/average values.

FAQs

Q: Can I get the memory stats for a specific key? A: No, Redis does not provide memory usage information on a per-key basis through PHPRedis. It provides the total memory usage of the entire database.