Debugging Memory Usage

Debugging memory usage on CentOS 7.

This page describes how to debug MariaDB's memory usage. It uses CentOS 7 but can be applied to other systems as well.

The idea is to employ Google PerfTools: https://gperftools.github.io/gperftools/heapprofile.html

On CentOS :

sudo yum install gperftools 
service mariadb stop
systemctl edit mariadb

This will open an editor.

Add this content and close the file:

[Service]
Environment="HEAPPROFILE=/tmp/heap-prof-1"
Environment="HEAP_PROFILE_ALLOCATION_INTERVAL=10737418240"
Environment="HEAP_PROFILE_INUSE_INTERVAL=1073741824"
Environment="LD_PRELOAD=/usr/lib64/libtcmalloc.so.4"

Then run

service mariadb start

Then, run the workload. When memory consumption becomes large enough, ruh

ls -la /tmp/heap-prof-*

This should show several files.

Copy away the last one of them:

cp /tmp/heap-prof-1.0007.heap .

Then, run

pprof --dot /usr/sbin/mysqld heap-prof-1.0007.heap  > 7.dot

(Note: this produces a lot of statements like /bin/addr2line: Dwarf Error: ... . Is this because it cannot find locations from the plugin .so files in mariadbd? Anyhow, this is not a showstopper at the moment)

Then, please send us the 7.dot file.