Jenkins active (exited)

Question

For some reason Jenkins stops working all the time and I have to restart jenkins service to make it work again. Every time this happens service is "active (exited)" but there is nothing in the logs. I use Ubuntu 16.04.

root@laran:~# service jenkins status
    ● jenkins.service - LSB: Start Jenkins at boot time
       Loaded: loaded (/etc/init.d/jenkins; bad; vendor preset: enabled)
       Active: active (exited) since Sun 2017-03-05 06:09:46 EST; 6min ago
         Docs: man:systemd-sysv-generator(8)
      Process: 25459 ExecStop=/etc/init.d/jenkins stop (code=exited, status=0/SUCCESS)
      Process: 25477 ExecStart=/etc/init.d/jenkins start (code=exited, status=0/SUCCESS)

Answer 1

Possibly the Linux kernel's oom-killer ("out-of memory killer") killed your JVM. It sends a SIGKILL signal to selected processes if the physical memory is no longer sufficient to accomodate all processes. Check that output of journalctl for lines containing the string oom-killer to confirm.

It is normal that the oom-killer strikes only after a certain period. Normally, Linux does not impose restrictions on the amount of virtual memory that a process requests (so your JVM can easily allocate 2 GiB of RAM on a 512 MiB system). However, if the process starts actually using the allocated memory (in your case: amount of used heap grows), then the kernel may find that the amount of physical memory is no longer sufficient. This is the point where the oom-killer will select a promising candiate process to be killed. Jenkins, as a non-system process that consumes a lot of memory, has very good chances to be the one that will be killed.

You can solve the situation by

• adding more physical memory to your system
• reducing JVM memory settings (e.g., smaller heap)