"received `killed` signal" during rspec

My circleCI is randomly failing each time when running rspec. It happens with 1x parallelism as well as 3x. I can’t pinpoint what it is and can’t see dmesg to see what’s going on because when I try to SSH into the container and dmesg I see:
dmesg: read kernel buffer failed: Operation not permitted

Here’s my relevant config.yml:

version: 2
    parallelism: 1
      - image: circleci/ruby:2.3-node
          - BUNDLE_PATH=vendor/bundle
          - BUNDLE_JOBS: 3
          - BUNDLE_RETRY: 3
          - RAILS_ENV=test
      - image: circleci/mysql:5.7-ram
          - MYSQL_DATABASE=blahblah
          - MYSQL_HOST=
          - MYSQL_ROOT_HOST=blahblah
          - MYSQL_USER=blahblah
          - MYSQL_ALLOW_EMPTY_PASSWORD=blahblah
      - image: elasticsearch:7.1.0
          xpack.security.enabled: false
          transport.host: localhost
          discovery.type: single-node
      - image: redis:4.0.1-alpine

When circleCI tries to do the “run rspec tests in parallel” step, it ends up running a few tests (never consistent how many) and then eventually dying with (don’t mind the warnings):

#!/bin/bash -eo pipefail
bundle exec rspec --format RspecJunitFormatter \
                  --out test_results/rspec.xml \
                  --format progress \
                  $(circleci tests glob "spec/**/*_spec.rb" | circleci tests split)
/home/circleci/project/vendor/bundle/gems/twitter-4.8.1/lib/twitter/cursor.rb:51: warning: circular argument reference - collection
/home/circleci/project/app/models/external_program.rb:45: warning: key :days_to_expiry is duplicated and overwritten on line 45
/home/circleci/project/app/models/external_program.rb:50: warning: key :dependent is duplicated and overwritten on line 50
Run options: include {:focus=>true}

All examples were filtered out; ignoring {:focus=>true}

Randomized with seed 34229
Received 'killed' signal

In addition to this, when I run the build manually while SSH-ed into the failed container, it runs the entire build and suite of tests successfully.