Bitbucket Server Process Dies Unexpectedly Due to Linux OOM-Killer
- Bitbucket Server is installed on a Linux host.
- The entire Bitbucket Server process suddenly terminates without warning. That is to say, the process ID (pid) is gone.
- The browser shows a generic "cannot connect" or similar error, indicating that it is not able to reach the webpage
- Nothing out of the ordinary appears in the Bitbucket Server application logs (
$BITBUCKET_HOME/logs/atlassian-bitbucket.log), since the application was terminated without properly shutting down
- Similarly, Tomcat logs (
<Bitbucket Server installation directory>/logs/catalina.out) also do not show errors
As of Bitbucket Server 5.x+, no logs are written to the BITBUCKET_INSTALL directory. The contents of catalina.out will be written to BITBUCKET_HOME/log/atlassian-bitbucket.log file.
Causes and Diagnosis
Bitbucket Server does not terminate its own pid unless a stop-bitbucket.sh is executed (which writes shutdown messages to the log). An unexpected pid termination clearly indicates the work of an external entity. Some examples include:
kill -9(user triggered or via script)
- Linux OOM-Killer
This KB article focuses on the Linux OOM-Killer, which is a feature on some Linux installations that will sacrifice processes to free up memory if the operating system experiences memory exhaustion for its own operations. Please note that this is different from Bitbucket Server running out of memory. In this case, the OS itself is in danger of running out of memory and thus starts terminating processes to avoid it.
On the host machine, look in the /var/log/ directory for the syslog or messages, and locate the timestamps spanning the approximate time when the pid was terminated. If you see entries similar to the following, then you know the process was a victim of the OOM-Killer:
Apr 8 11:29:48 bitbucket01 kernel: Out of memory: Kill process 1386 (java) score 358 or sacrifice Apr 8 11:29:48 bitbucket01 kernel: Killed process 5388, UID 4048, (java) total-vm:1331564kB, anon Apr 8 11:29:51 bitbucket01 kernel: java invoked oom-killer: gfp_mask=0x200da, order=0, oom_adj=0,
The way to mitigate this type issue is to Add Swap Space to the system. This will keep Bitbucket from crashing while working on the resolution. This can be done live without having to stop Linux or Bitbucket. This will have performance impacts on Bitbucket so this should only be used to prevent a full outage.
Decide where on the disk there is available space. This example will put the swap space in the root user's home directory.
Create a file on the local disk. This is an example of 2G swap file:
Change the permission of the swap file so that only root can access it.
Make and enable this file as a swap file using mkswap command.
Verify whether the newly created swap area is available for your use.
In the case of the OOM-Killer, the possible resolutions would be to:
Increase the amount of memory available on the host machine itself.
- Decrease the amount of memory allocated to Bitbucket Server or competing processes on the machine.
- Disable the OOM-Killer (not recommended).
Additional info on how the OOM-Killer operates, please see: http://prefetch.net/blog/index.php/2009/09/30/how-the-linux-oom-killer-works/