How can I detect what is reason of lag?

I created multiplayer game using node, socket.io and node workers. Clients connect to index.js. Workers represent game worlds. My game is only thing i coded in node. Production server is heroku.​When I play game on production server I sometimes experience some lag, sometimes too bad lag. By lag I mean when server don't respect soon enough commands from client or I see in client too big latency. This lag happen probably when more players play game. But I have no idea why and when exactly lag happen. How can I detect when and why happen lag on my production server. I have currently no idea what is happening on server.

Submitted May 21, 2019 at 05:17PM by aqzaqzaqz