Unfortunately, I don't know how to reproduce this. 

Symptoms:

1. I'm getting these errors in /var/log/zabbix/zabbix_server.log:
   562182:20190717:180358.072 [Z3005] query failed: [2013] Lost connection to MySQL server during query [update problem set r_eventid=368546388,r_clock=1563375754,r_ns=235192960,userid=0 where eventid=
   367996910;
   update problem set r_eventid=368546387,r_clock=1563375754,r_ns=245660521,userid=0 where eventid=367990352;
   update problem set r_eventid=368546386,r_clock=1563375766,r_ns=733935539,userid=0 where eventid=368336399;
2. "netstat -anlp | grep :6033 | grep TIME_WAIT -wc" shows 20000+ TIME_WAIT connections to my proxysql mysql load balancer. When I "kill -9 zabbix_server", this number goes down to the normal 500-100.

I suspect that some weird error is happening on the side of proxysql, however zabbix_server tries to immediately create a new connection to the proxysql load balancer and that's what's worrying me.

Is there a way to slow it down?