Steps to reproduce:

1. Please set up Zabbix6.0 according to the following document.
   https://www.zabbix.com/download?zabbix=6.0&os_distribution=alma_linux&os_version=8&components=server_frontend_agent&db=pgsql&ws=apache
   
   Note

   The verification was done with postgresql, but a similar problem occurred with mysql as well.

   
   

2. Set the following item.

   log[/var/log/messages,"(err)|(recover)"]
   

   
   

3. Set the following trigger.

   Expression
   　find(/Zabbix server/log[/var/log/messages,"(err)|(recover)"],,"regexp","err")=1
   PROBLEM event generation mode
   　Multiple  
   

   
   

4. generate a large number of trigger events
   
   • example)Output a large amount of target keywords to the log using the “logger” command

     $ for i in {1..500000};do logger "errorA $i" ;done
     

     Note

     rsyslog may freeze so you have to run "systemctl restart rsyslog" every time

Result:
The vsz value output by the following command will increase.

ps -eo vsz,comm,euser,args

It seems that recovering the trigger event does not free the memory.

• graph
  
• log
  zabbix_server.log（trace log)

  32296:20240814:135204.742 problem events : 484875 (670849 slots)
  32296:20240814:135217.276 problem events : 484879 (670849 slots)
  32296:20240814:135229.750 problem events : 484883 (670849 slots)
  32296:20240814:155214.091 problem events : 866277 (1509427 slots)
  32296:20240814:163337.834 problem events : 0 (1509427 slots)　　←Slots do not decrease even after event recovery
  32296:20240814:163342.860 problem events : 0 (1509427 slots)
  32296:20240814:163347.876 problem events : 0 (1509427 slots)
  32296:20240814:163352.907 problem events : 0 (1509427 slots)
  32296:20240814:175004.716 problem events : 0 (1509427 slots)
  32296:20240814:174530.551 problem events : 239796 (1509427 slots)　←Even if an event occurs, the slot will not increase by the amount that can be covered by the increase slot.
  32296:20240814:174537.471 problem events : 239796 (1509427 slots)
  797268:20240816:163354.922 problem events : 233774 (298153 slots)　←It is released once when the service is restarted, but if there are many events, it will be loaded immediately after startup, so it will increase quickly.
  797268:20240816:163401.682 problem events : 233777 (298153 slots)
  797268:20240816:171640.382 problem events : 437874 (670849 slots)
  1207:20240823:175048.334 problem events : 1354135 (2264149 slots)
  1207:20240823:175048.334 problem events : 1354135 (2264149 slots)
  400721:20240823:183049.364 problem events : 1354135 (2264149 slots)　←Service resumed. Same as above.
  401478:20240823:183600.106 problem events : 1354135 (2264149 slots)
  401860:20240823:184246.547 problem events : 1354135 (2264149 slots)
  401860:20240827:160522.204 problem events : 1354144 (2264149 slots)
  401860:20240827:161302.397 problem events : 1 (2264149 slots)
  401860:20240827:181853.195 problem events : 1 (2264149 slots)
  401860:20240828:175200.411 problem events : 3 (2264149 slots)
  670438:20240828:175519.163 problem events : 3 (1009 slots)　←Service resumed. Since there are few events, the number of slots will not increase.