Recently we encountered some strange issues with httpd on some of our CentOS 7 machines during my current project.
Through our pipeline we restart httpd several times which sometimes leads to this error:
Apache: [error] (28)No space left on device
After some research we found out the semaphores were all being used blocking httpd daemon to restart.
The list of semaphores can be fetched by issuing
# ipcs -st ------ Semaphore Operation/Change Times -------- semid owner last-op last-changed 753664 apache Not set Mon Feb 17 20:20:47 2020 786433 apache Not set Mon Feb 17 20:20:47 2020 720898 …