Troubleshooting Backend API Memory Leaks

• Overview: Step-by-step troubleshooting and remediation process for a memory leak causing RAM usage to spike to 95% after 6 hours of uptime in backend applications.
• Symptom: The API performs perfectly after deployment, but after approximately 6 hours, memory usage spikes to 95%. Restarting the server only provides a temporary fix.
• Root Cause: The application suffers from a memory leak or resource congestion due to continuous memory allocation without proper release or Garbage Collection (GC).

Investigation & Diagnostic Steps

1. Metrics & APM Data Collection: Check monitoring tools to see if the RAM increase correlates with a specific endpoint, traffic spike, or background job.
2. Capture Heap Dumps: Take a heap dump when RAM reaches high thresholds (95%) and compare it against a baseline snapshot taken right after startup to identify objects growing abnormally in count or size.
3. Profiling: Run language-specific profiling tools (such as pprof, Node.js heap snapshots, Java Flight Recorder, etc.) to trace which functions or modules are holding onto references.

Common Culprits to Check

• Unbounded Caches: In-memory caches lacking a maximum size limit or Time-To-Live (TTL).
• Event Listeners: Event listeners that are registered but never properly unsubscribed after use.
• Connection Pools: Database or HTTP client connections that are not closed correctly.
• Global Variables / Singletons: Accumulating state indefinitely across requests.
• Background Workers: Processing queues that run slower than the rate of incoming tasks, causing queues to swell in RAM.