Hi All,
I am working on Drupal 8.2.0-dev for website on linux server with MariaDB as database server. The site setup is based on 3 instances of website setup or file system using one database. Whenever updates are made to the site cache is cleared from all 3 instances / nodes for changes to work properly esp. twig template changes.
Here is more detail about site configuration on server :-
The website is actually a 3-node cluster behind a load balancer.
Each node (node1,node2 and node3) are part of a MariaDB Galera Cluster, and each node is hosting the Drupal website.
Each drupal website communicates with it’s own DB. So this means when node1 is serving a page, it is reading/writing to the DB on node1. Likewise, node2 read/writes to node2’s DB and so on.
The website files on main location are replicated between the nodes using lsyncd and csync2.
So, when a visitor hits the website, traffic flow is :
HTTP Traffic -> HAPROXY Load Balancer -> (one of the 3 Nodes)
a. Node1 website communication to MariaDB on node1 (localhost)
b. Node2 website communication to MariaDB on node2 (localhost)
c. Node3 website communication to MariaDB on node3 (localhost)
I face an error :-
1. While using drupal admin interface for making updates or inserts website admin often gets error below.
2. Wen cache is cleared using Drush on website on the frontend also.
Uncaught PHP Exception Drupal\\Core\\Database\\DatabaseExceptionWrapper: "SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction: INSERT INTO {cache_entity} (cid, expire, created, tags, checksum, data, serialized) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6) ON DUPLICATE KEY UPDATE cid = VALUES(cid), expire = VALUES(expire), created = VALUES(created), tags = VALUES(tags), checksum = VALUES(checksum), data = VALUES(data), serialized = VALUES(serialized); Array, referer:
After searching on similar issues I found that solution suggested are using modules which are not ported to Drupal 8 yet e.g.
https://www.drupal.org/project/apdqc →
. This issue was reported for Drupal 7 several times but not Drupal 8. I am not sure if its bug so adding support request.
Have not been able to find any reliable solution for this.
Just to add in my case the deadlock always is related to cache tables. Also can "Entity/field definitions" , " Mismatched entity and/or field definitions " as on page /admin/reports/status has any relation to this?
Any suggestions would be appreciated.
Thanks
Atul