Very high usage of CPU that creates high iowait

Thatoo commented 3 years ago

Describe the bug

Synapse v 1.35 is using very high CPU and create high iowait

Context

Hardware: Old laptop or computer
YunoHost version: 4.2.6.1
I have access to my server: Through SSH | through the webadmin | direct access via keyboard / screen | ...
Are you in a special context or did you perform some particular tweaking on your YunoHost instance?: no

Steps to reproduce

Have synapse service down
connect to ssh
glances
cpu usage low and no iowait
start synapse service
cpu usage becomes crazy and iowait too, won't reduce with time

Expected behavior

CPU usage should increase a bit but not that much and iowait should reduce below 1 soon

Logs

https://paste.yunohost.org/ivedupejer

Thatoo commented 3 years ago

I discovered that because I'm experimenting problem to decrypt message coming from matrix.org friend's account. Encrypted message from my home server and an other small server are well decrypted and room are fast but encrypted message from matrix.org can't be decrypted and matrix.org room are slow...

I have no idea if their is a link between the two problems so I'm not entirely sure it's relevant but I feel it does because it happened at the same time. Few days ago, I didn't have any problem with any room or encryption and I didn't notice any high CPU/iowait problem. I was checking when I updated nextcloud from 20.0.8~ynh1 to 21.0.2~ynh1 because it didn't happen smoothly : https://github.com/YunoHost-Apps/nextcloud_ynh/issues/419#issuecomment-868435491

Could it be linked to these steps we have to do in order to operate nextcloud update (does it have an impact on synapse?)? :

$ php7.3 -i | grep apc.enable
apc.enable_cli => Off => Off
apc.enabled => On => On
$ # added apc.enable_cli=1 to /etc/php/7.3/cli/conf.d/20-apcu.ini
$ sudo service php7.3-fpm restart
$ php7.3 -i | grep apc.enable
apc.enable_cli => On => On
apc.enabled => On => On

Thatoo commented 3 years ago

Or could it be linked to

Over the last few days we've seen a distributed spam attack across the public Matrix network, where large numbers of spambots have been registered across servers with open registration and then used to flood abusive traffic into rooms such as Matrix HQ.

https://matrix.org/blog/2021/06/30/security-update-synapse-1-37-1-released

Thatoo commented 3 years ago

It was indeed linked to matrix.org server spam situation. As soon as I left the room #matrix:matrix.org , all problems disappeared

.

YunoHost-Apps / synapse_ynh