Welcome the Technical Support section. Help us in assisting you by providing us with a concise and descriptive elaboration of your issues. Be specific and if possible, provide us with a step-by-step instruction in replicating your problem.
in some module adaptation, i am using jomsocial public functions like getOnlineusers.
with little limit value (<100) i don't see any issue, it has good behaviour, but when i set a limit to 500 or 1000 members to retrieve, then i get massive error 500 in the site.
What would you recommend in terms of php or apache settings or mysql to make it work good and not break.
The query is really huge to fetch that amount data. you need to contact your sys-admin to tweak your site, my suggesttion dont do this! hehe, because it will make your site slower.