Go "fatal error: runtime: out of memory" in CI

By Daniel Zoghalchali·Latchkey

The Go runtime aborted because the OS refused a memory request. In CI this happens when a build, test, or data job exceeds the runner RAM (or a container memory limit).

What this error means

A Go step prints fatal error: runtime: out of memory with a runtime stack and exits. Lowering parallelism or using a larger runner clears a one-off spike with no code change.

shell

fatal error: runtime: out of memory

runtime stack:
runtime.throw({0x...})
	/usr/local/go/src/runtime/panic.go:1047

Common causes

The job exceeded available RAM

A large go test ./..., race-detector run, or data load can spike past the runner memory.

A container or cgroup limit

A --memory limit caps the runtime even when the host has free RAM.

How to fix it

Lower memory pressure

Reduce concurrency and disable the memory-heavy race detector where not needed.

shell

go test -p 2 ./...        # fewer parallel packages
# avoid -race in memory-tight jobs
GOMEMLIMIT=3GiB go build ./...

Right-size the runner

Move memory-heavy Go jobs to a runner with more RAM.
Raise or remove a tight container --memory limit.
Split very large test runs into smaller jobs.

How to prevent it

Set GOMEMLIMIT to keep the runtime under the ceiling.
Bound go test parallelism in CI.
Right-size memory for race-detector runs.

Frequently asked questions

What causes "Go runtime OOM"?

A large go test ./..., race-detector run, or data load can spike past the runner memory.

How do I fix Go runtime OOM?