Troubleshooting Occasional Connection and Job Timeout Issues in a Laravel, MariaDB, and Redis Setup

If you’re managing a Laravel-based real estate listings platform that automates offer imports via various CRM integrations, encountering intermittent connection disruptions can be quite challenging. Recently, some users have experienced sporadic timeouts both during database interactions and job processing, despite seemingly modest server loads. Here’s a comprehensive overview and some actionable insights to help diagnose and resolve these issues.

System Overview

Your current environment consists of:
– A single VPS hosting the Laravel application, MariaDB database, and Redis cache.
– Hardware specs include 8 CPU cores and 16 GB of RAM.
– Typical traffic is low, around 20 visits per minute, with occasional quick bursts from bots.
– The application is designed for cost efficiency, with plans to expand into microservices as demand increases in the future.

Nature of the Problems

• Job Processing Timeouts: Occasionally, queued jobs exceed the PHP timeout limit of 600 seconds, though daily job durations are often under a second.
• External API Timeouts: Curl requests to a connected WordPress instance also sporadically timeout, hinting at potential connection stability issues with the database or network components.

Initial Troubleshooting Steps Taken

• PHP Pools: Verified that PHP-FPM pools are properly configured, and request handling capacity is sufficient.
• MariaDB Configuration: Checked that maximum connection limits are not being saturated; timeout settings are generous, with a 12-hour wait time configured.
• Slow Query Logging: Enabled to track slow database operations. Observations indicate no significant or recurring slow queries; logs primarily show method calls that get stuck.

Potential Causes and Recommendations

Although the setup appears sound, intermittent timeouts often stem from underlying network, resource contention, or misconfiguration issues. Consider the following steps:

1. Network Stability & External API Calls
2. Monitor curl and API request logs to identify patterns or recurring failures.
3. Implement retries with exponential backoff to handle transient network issues.

4. Use tools like mtr, ping, or traceroute to check for network latency or packet loss between your app and external services.

5. Database Connection Health

6. Check MariaDB’s status metrics (SHOW STATUS LIKE 'Threads_connected';, SHOW VARIABLES LIKE 'max_connections';) to ensure connection caps aren’t being hit.
7. Enable the MariaDB performance_schema for more