Just Another Reason to Love Gab Davis… From her blog post on the Turtle Partnership’s Blog…
To summarize, the Presence Subscription service in the 8.5 Community server is now trying to utilize too much memory, and needs to be throttled back on many 32bit systems. This is achieved by modifying the sametime.ini as prescribed in her post.
The fix should be to modify the sametime.ini file and replace this
STPresenceSubscriptionsMgr_VM_ARGS=-Xmx1024m -Xgcpolicy:gencon -Xcompactgc
STPresenceSubscriptionsMgr_VM_ARGS=-Xmx512m -Xgcpolicy:gencon –Xcompactgc
It should go without saying, but restart your community server.