CircleCI job killed

April 30, 2026 · View on GitHub

Playbook ID: circleci-resource-class-oom Category: ci Severity: critical Tags: circleci, oom, memory, resource-class, ci

What this failure means

The CircleCI job was killed because it exceeded the memory limit of the selected resource class. The process received SIGKILL or the container was OOM-killed by the kernel, and the job exited non-zero without a clear user-visible error.

Common log signals

exit code: 137
Out of memory: Kill process
OOM killer
Killed
Process killed
exit status 137
SIGKILL
java.lang.OutOfMemoryError

Diagnosis

CircleCI jobs run in containers with a fixed memory ceiling determined by the resource class. When the job exceeds that ceiling, the kernel OOM killer terminates one or more processes. The failure typically appears as:

  • A process exits with signal 9 (SIGKILL) or a non-zero code with no error message.
  • The log ends abruptly or shows Killed without a stack trace.
  • CircleCI emits exit code: 137 (128 + SIGKILL).
  • A test runner or build tool exits with OOM Killer or Out of memory: Kill process.

Common causes include: large in-memory test suites with too much parallelism, Node.js builds without a --max-old-space-size flag, Docker-in-Docker image pulls inside small containers, or Maven/Gradle builds that default to large JVM heap sizes.

Fix steps

  1. Upgrade the resource class in .circleci/config.yml:

    jobs:
  build:
    resource_class: medium+   # or large, xlarge, 2xlarge

  2. For Node.js builds, cap the V8 heap explicitly:

    - run: NODE_OPTIONS=--max-old-space-size=2048 npm run build

  3. For JVM-based builds (Maven, Gradle), set a bounded heap:

    MAVEN_OPTS="-Xmx1g" mvn package
GRADLE_OPTS="-Xmx1g" gradle build

  4. Reduce test parallelism so each worker uses less memory simultaneously:

    parallelism: 2    # lower from 4 or 8

  5. Split long test suites across separate jobs and use CircleCI's test splitting to keep each job within budget.

  6. Add a memory monitoring step before the failing command:

    free -h

Validation

  • Re-run the job and confirm no exit code: 137, Killed, or OOM message appears.
  • Verify free -h at job start shows adequate available memory for the workload.

Likely files to inspect

  • .circleci/config.yml

Run Faultline

faultline analyze build.log
faultline explain circleci-resource-class-oom
faultline workflow build.log --json --mode agent

Search phrases this page answers

  • CircleCI job killed — resource class memory limit exceeded
  • Ci: circleci job killed — resource class memory limit exceeded
  • Fatal error: CALL_AND_RETRY_LAST Allocation failed
  • GitHub Actions circleci job killed — resource class memory limit exceeded
  • faultline explain circleci-resource-class-oom

Generated from playbooks/bundled/log/ci/circleci-resource-class-oom.yaml. Do not edit directly — run make docs-generate.