Summary

When running Confluence, we can see some (or all) of the following symptoms:

• Confluence fails to start sometimes
• Slow performance
• Memory is allocated at a fast rate
• Long Garbage Collection times

Environment

The issue described on article only applies to Confluence when running on a virtual machine such as VMWare.

Diagnosis

When checking the Confluence logs, an error similar to the following can be found:

OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x000000079e000000, 4194304, 0) failed; error='Not enough space' (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 4194304 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /app/atlassian/confluence/bin/hs_err_pid11193.log

This error may also be displayed on the terminal, when stopping Confluence manually.

Cause

Memory Reservation is not enabled for the VM, which may prevent Confluence from getting sufficient memory allocated to it in a timely manner.

Solution

Memory Reservation

Enable Memory Reservation for the VM.

Increase Max Map

If unable to work with memory reservation, see if the OS is configured to allow sufficient memory for the JVM to work.

On some Linux distros, this is:

cat /proc/sys/vm/max_map_count

Increase it to the amount of Heap + threshold. Some customers go to 1.5 the Heap size configured to the JVM (Xmx Java opt).

On some distros, this is achieved through (replace 99999 by the amount of memory, like 1.5 the Xmx):

sysctl -w vm.max_map_count=99999

Workaround

Setting Confluence's base and maximum heap size (eg. Xmx and Xms) to the same memory value can also help with this issue:

• How to fix out of memory errors by increasing available memory

Related content

• Running Confluence in a Virtualized Environment
• Understanding VMware Reservations Limits and Shares