A long operation (image conversion) blocks the server, what should I do?

Question

JavaScript

It was time for tests and it turned out that when one long operation is performed (image conversion takes about 30-60 seconds), the entire server is blocked and it is impossible, for example, to log in to anyone at all.
What to do? Where to look for an error? How to be in that case? There is a lot of code. Wherever you can promises and asink aveites. Why is it blocking? How about non-blocking blablabla?

Answer 1

there is no error: this is a feature of the event loop - there should not be long operations because they block the entire stream.
convert separately from the main stream.