We encounter a problem with the history syncer process. The history syncer process reaches 100% CPU while processing log items. According to the process information it takes always around 60 seconds to import a few 100 items. As a result the history write cache decreases.

After doing a lot of tests, I may exclude issues with the DB. There are also no slow queries reported. Checking the process with strace I notice that the process is doing constantly semop and brk operations very fast. (see attachements)

Also the debuglog of the zabbix-server reports constantly substitute functions.

We encounter the issue with Zabbix 3.2 and 3.4.

I think there is an issue on processing logdata.