MySQL server has gone away, where to dig?

Question

PHP

Good afternoon.
When developing the project, I encountered the following problem: the MySQL server has gone away error periodically falls out.
How to deal with it and where to dig?
PHP, MySQL via PDO, Debian
Crashes intermittently on a simple UPDATE query on a single record in a table with about a million records. That is, sometimes the update takes 1 ms, sometimes 5, and sometimes everything ends with an error.
If you catch an exception and execute the request again, everything passes, but these are some half-measures.

Answer 1

The reasons may be different. When I encountered this, one of two things helped me:
1. If you use a database connection pool (I don’t remember what it’s called in PDO, it seems like a persistent connection or something like that ...), then try disabling it
2. In the settings muskla try to increase the max_allowed_packet parameter
But to be honest, I'm not sure if this is your case, although anything can be

Answer 2

You don't have a digital ocean virtual machine by any chance?

Answer 3

service mysql restart
Log into phpmyadmin as root and open the processes tab. There you can see sql queries that slow down