# install parallel first (sudo apt-get install -y parallel)

JOB_NUM=10
NAME_FILTER='*'

# stop instances
gcloud compute instances list --filter=name:$NAME_FILTER | awk '/RUNNING/ {printf "gcloud -q compute instances stop %s --zone %s;\n", $1, $2 > "stop-instances.txt" }'
parallel --jobs $JOB_NUM < stop-instances.txt

# remove delete protection 
gcloud compute instances list --filter=name:$NAME_FILTER | awk '/TERMINATED/ {printf "gcloud -q compute instances update %s --no-deletion-protection --zone %s;\n", $1, $2 > "remove-protection.txt" }'
parallel --jobs $JOB_NUM < remove-protection.txt

# delete instances
gcloud compute instances list --filter=name:$NAME_FILTER | awk '/TERMINATED/ {printf "gcloud -q compute instances delete %s --zone %s;\n", $1, $2 > "delete-instances.txt" }'
parallel --jobs $JOB_NUM < delete-instances.txt