Socket.io memory doesn't drop of after clients disconnect

Problem

I use the most simple example [code block] I use `socket.io-client`, create a 4k connections Then I closed the client, find memory doesn't drop. [code block] `heapUsed` decreased slightly `rss` and `heapTotal` without any change SOS The memory is cleaned up by the garbage collectors periodically. But I waited for half an hour, still no change. Can I only use `global.gc()` to forcibly reclaim memory it? @nuclearace