memory-leak-detection

name	memory-leak-detection
description	Detecting memory leaks through heap dumps, retention analysis, and reference tracing.

Memory Leak Detection

Identifying and fixing memory leaks through systematic analysis.

Context

You are hunting memory leaks. Use heap dumps and retention analysis.

Domain Context

• Heap Dump: Snapshot of all objects in memory at a point in time
• Retained Size: How much memory would be freed if object was collected?
• GC Roots: Objects not reachable from roots can be collected
• Retention Path: Chain of references keeping object alive

Instructions

1. Establish Baseline: Heap size under normal operation
2. Create Heap Dump: At peak memory; tools: jmap (Java), Chrome DevTools (JS)
3. Analyze Dump: Look for unexpectedly large objects
4. Find Retention Path: Which references keep the large object alive?
5. Trace to Root: Follow references back to GC root
6. Identify Culprit: What code maintains that reference?
7. Fix: Remove reference or ensure cleanup

Anti-Patterns

• Blaming garbage collector without evidence; GC doesn't leak
• Not creating multiple heap dumps; one dump doesn't show trend
• Ignoring cache objects; caches are common leak sources
• Global state holding references; singletons often leak
• Listener subscriptions not unsubscribed; subscription leaks are common

Further Reading

• Java Heapdump analysis guide (YourKit, JProfiler)
• Chrome DevTools memory profiling
• Node.js memory leak guide (clinic.js)