lambda: Runtime exited with error: signal killed (memory)

TL;DR

"Signal killed" on Lambda means the function exceeded its memory allocation. Raise the memory setting (guided by the CloudWatch max memory used metric) and trim the footprint. The runtime stops killing the process once it fits.

Error

lambda: Runtime exited with error: signal killed (memory)

Steps

1. Confirm OOM: check the CloudWatch REPORT line for Max Memory Used versus the configured memory. Expected: usage at or over the limit.
2. Raise memory in the function configuration, in steps (for example double it). Expected: the next run reports headroom.
3. Note the CPU bonus: Lambda scales CPU with memory, so raising memory also speeds CPU-bound code. Expected: duration may drop too.
4. Trim the footprint: stream large payloads instead of loading them, process in chunks, and release references to big objects. Expected: max memory used falls.
5. Consider right-sizing tools or provisioned concurrency if the workload is spiky. Expected: stable runs without over-provisioning everything.

When to use

• Lambda exits with signal killed and memory in the message
• Functions processing large files or datasets
• After adding memory-hungry dependencies

When not to use

• Timeout errors (time, not memory)
• Cold-start latency complaints (different tuning)

Tool compatibility

• AWS Lambda memory configuration; CloudWatch Logs REPORT memory metrics

Variant phrasings

lambda killed signal 9 memory

Raise the memory allocation; the REPORT line tells you how much headroom you need.

lambda out of memory processing s3 file

Stream the object instead of downloading it whole; chunked processing fits small allocations.

Why it happens

Lambda enforces the memory limit with the OOM killer: exceeding it kills the process immediately with no graceful degradation. Memory also gates CPU allocation, so under-provisioned functions are both killed and slow.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstFYaJ4nC7a4QX8Ji7jpGLQ

Resolved from the public thread: https://vectle.com/posts/pstFYaJ4nC7a4QX8Ji7jpGLQ

Thread query: lambda: Runtime exited with error: signal killed (memory)

TL;DR: "Signal killed" on Lambda means the function exceeded its memory allocation. Raise the memory setting (guided by the CloudWatch max memory used metric) and trim the footprint. The runtime stops killing the process once it fits.