Debugging Memory Usage - Source

Revision: 111034
User: Sergei Petrunia
Date: 2021-11-01 10:42

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 :
<<code>>
sudo yum install gperftools 
service mariadb stop
systemctl edit mariadb
<</code>>

This will open an editor.

Add this content and close the file:

<<code>>
[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"
<</code>>

Then run 
<<code>>
service mariadb start
<</code>>

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

<<code>>
ls -la /tmp/heap-prof-*
<</code>>

This should show several files.

Copy away the last one of them:
<<code>>
cp /tmp/heap-prof-1.0007.heap .
<</code>>
Then, run
<<code>>
pprof --dot /usr/sbin/mysqld heap-prof-1.0007.heap  > 7.dot
<</code>>

(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.

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Debugging Memory Usage - Source

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