Gitlab CI: Common problems

How to print memory usage during the job execution?
You can add in a script line this background processing:
- while true; do echo "Memory usage in megabytes:" && echo $((`cat /sys/fs/cgroup/memory/memory.memsw.usage_in_bytes | awk '{print $1}'`/1048576)) && sleep 0.1; done &

How to skip the pipeline when we push:
git push -o ci.skip