huge SubtransSLRU and SubtransBuffer wait_event

[James Pang (chaolpan)]

Hi,
   We have a Postgresqlv14.8 server, client use Postgresql JDBC connections, 
today, our server see a lot of  "SubtransBuffer" and "SubtransSLRU" wait_event. 
Could you help direct me what's the possible cause and how to resolve this 
waits ?

Thanks,

James