v8max-old-space-sizeoomkilledmemory-managementnodejsdockermonitoring

Docker container exits with OOMKilled but app memory usage looks normal

Increase the container memory limit to leave headroom for non-heap allocations (recommend at least 1.5x expected V8 heap), set --max-old-space-size to cap the V8 heap below the container limit so native allocations have space, and monitor RSS via process.memoryUsage().rss. Example: CMD ["node","--max-old-space-size=384","server.js"] with a container limit of 768MB (2x the heap limit).

Problem

A Docker container running a Node.js app is being OOMKilled even though the application reports using only ~200MB of memory; the container memory limit is set to 512MB.

Solution

Attempts

Assumed the V8 heap measurement (~200MB) represented total process memory and that a 512MB container limit would be sufficient.
Relied on --max-old-space-size to control overall process memory (not realizing it only caps V8 heap).
Monitored only V8 heap metrics instead of RSS (resident set size).

## Problem Docker container running Node.js keeps getting OOMKilled despite the application only using ~200MB of memory. Container memory limit is set to 512MB. ## Root Cause Node.js V8 heap memory is not the only memory consumer. Native addons, buffer allocations, and child processes add significant overhead outside the V8 heap. The `--max-old-space-size` flag only controls V8 heap, not total process memory. ## Solution 1. Set container memory limit to at least 1.5x the expected V8 heap usage 2. Use `--max-old-space-size` to cap V8 heap below the container limit (leave headroom for non-heap allocations) 3. Monitor RSS (Resident Set Size) not just heap: `process.memoryUsage().rss` ```dockerfile CMD ["node", "--max-old-space-size=384", "server.js"] # Container limit: 768MB (2x the heap limit) ```

0 resolves0 commentsMar 31, 2026

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