Understanding and Resolving Occasional Connection and Job Processing Timeouts in a Laravel-MariaDB-Redis Deployment

Introduction

In modern web application development, ensuring smooth and reliable database and service interactions is paramount. When working with Laravel-based applications that integrate MariaDB and Redis, encountering sporadic connection timeouts and job processing delays can be particularly challenging, especially when system load appears minimal. This article explores common causes for such issues and provides actionable strategies to diagnose and resolve them, tailored to a typical small-scale deployment.

Scenario Overview

Consider a Laravel application deployed on a single VPS, managing real estate listings with automated import capabilities from external CRMs. The server configuration includes:

• Hardware: 8 CPU cores, 16 GB RAM

• Software: Laravel framework with MariaDB and Redis, plus integration with a WordPress (WP) instance for content retrieval

• Load: Low traffic (~20 visits per minute), with occasional bursts from bots (10-15 concurrent connections briefly)

The application infrastructure is currently monolithic, with plans to transition toward microservices as demand increases. This setup prioritizes cost-efficiency, but it has led to intermittent issues, notably:

• Job processing timeouts (set to 600 seconds) occurring sporadically, despite average processing times being around 0.5 seconds

• API connection timeouts when interfacing with the WP instance via cURL, which are inconsistent

These symptoms suggest potential instability in database connections, possibly involving MariaDB, Redis, or network components.

Diagnosing the Root Causes

1. Connection Handling and Pool Limits

Despite configuring PHP pools adequately, it’s essential to verify that the application’s connection management aligns with workload demands. Overly aggressive or insufficient connection pooling, or misconfigured timeouts, can cause connections to deadlock or timeout under load.

1. MariaDB Configuration

2. Max Connections: Check that MariaDB’s max_connections parameter is sufficiently high relative to peak concurrent connections, especially during burst traffic.

3. Timeout Settings: Ensure wait_timeout, interactive_timeout, and net_read_timeout are configured appropriately. Excessively long timeouts (like your 12-hour limit) may cause issues if connections are left hanging.

4. Connection Queue: Monitor MariaDB’s status variables (Threads_connected, Max_used_connections) to detect saturation or spikes.

5. PHP and Laravel Settings

6. Worker Timeouts: Confirm PHP-FPM worker timeouts are set correctly