MariaDB 10.2.14 (Got timeout reading communication packets)

I am seeing warning messages in my MariaDB server logs. I have tried many things.

I have optimize and repair all of my databases but warning are still there.

2018-04-19 22:50:14 139673358411520 [Warning] Aborted connection 473891 to db: 'admin_' user: 'admin_' host: 'localhost' (Got timeout reading communication packets)

2018-04-19 22:52:43 139672739514112 [Warning] Aborted connection 474608 to db: 'admin_' user: 'admin_' host: 'localhost' (Got timeout reading communication packets)

My my.cnf

skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 500M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
thread_concurrency = 8

innodb_file_per_table

max_connections=500
wait_timeout=60
interactive_timeout=60
long_query_time=5

I am using CentOS 7 with 8 GB of RAM.

Can someone help me?

Solve this problem by reading the https://mariadb.com/kb/en/library/upgrading-from-mariadb-101-to-mariadb-102/ incompatibilities web page. The problem has existed in past releases because log_warnings use to default to 1 and now default to 2.

Dynamically set global log_warnings=1; and watch the messages stop almost immediately, reset to 2 and within 3-5 minutes the messages resume.

This explains why 10.2.14 they just show up, yet the real problems most likely related to improper application exception handling.

Suggestions to consider for your my.cnf-ini [mysqld] section

Lead with # or REMOVE to allow defaults to work for you. . sort_buffer_size . read_buffer_size . read_rnd_buffer_size . thread_concurrency

change this global variable

thread_cache_size=100  # from 8 to reduce threads_created count

You have wait_timeout=60 in the settings. It means that connections that are idle for 60 seconds, are aborted. Increase the value to fix the problem.

Reference: https://mariadb.com/docs/reference/mdb/system-variables/wait_timeout/