How does Cache::remember work, and how do Atomic Locks protect a server?

Short answer

Cache::remember checks for the key and returns it if found; otherwise, it runs a Closure and stores the result for the specified duration. Atomic Locks ensure only one request performs an expensive operation at a time.

Explanation

Cache::remember is the most common way to store slow query results. However, when a popular key expires on a site receiving thousands of visits, hundreds of requests may simultaneously recalculate the same result and query the database (a Cache Stampede). Cache::lock()->get() ensures that only one request updates the cache while the others wait for the ready result.

Code example

$users = Cache::remember('users.active', now()->addHours(1), function () {
    return User::where('active', true)->get();
});

Common mistakes

• Storing large Eloquent model objects with unloaded relationships in the cache, causing Serialization errors.

Follow-up questions

• What is Probabilistic Early Expiration, and how does it prevent a cache stampede?
• What are the main production performance commands (route:cache, view:cache, config:cache)?

Sources

• Laravel docs — Cache: Retrieve & Store