850185 - [Workers] postMessage is sometimes slower than JSON.stringify

Status: RESOLVED WORKSFORME

(Core :: DOM: Workers, enhancement, P3)

Description

[David Teller [:Yoric] - still alive but not very active]

While attempting to improve bug 850184, I have run a few benchmarks on JSON.stringify + TextEncode vs postMessage for huge JSON objects. Some of the results are surprising. As it turns out, in my test case, JSON.stringify is faster than postMessage. I suspect that this is not expected.

Comment 1

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

I don't understand what you're trying to compare here.  postMessage sends stuff to a different thread, JSON.stringify doesn't, no?

Comment 2

[David Teller [:Yoric] - still alive but not very active]

Yes, I was just surprised because I expect that, for a huge object, the cost of serialization in postMessage dominates any other cost cost. If my understanding is correct, I am therefore comparing two serialization mechanisms: postMessage's and JSON.stringify. Given that JSON.stringify is anything but optimal, I expected postMessage's algorithm to be quite faster.

Comment 3

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Well we haven't really tried to optimize structured cloning.  A profile would be useful here.

Comment 4

[Marion Daly [:mdaly]]

Worth investigating in the future.

Comment 5

[Andrew Sutherland [:asuth] (he/him)]

I think we've seen some nice improvements to serialization performance in the past decade but to comment 1's point we also fundamentally are doing a very different thing, in particular, we do expect JSON stringify performance to do better with large strings where ropes can be used, etc. (We've also seen JSON stringify performance concerns from objects with a lot of keys/values.)