Spawn (extra) users inside a running Task(Set)?

[aukevanleeuwen]

Hello,

I have a bit of an odd request: is it possible to spawn extra users from within a running user's task? The question behind the question is that I'm testing a fraud detection system. I was thinking about having 'regular' traffic, however, with a certain (low) chance I would like a secondary 'fraud user' to arrive on the scene. At that moment I need data from one of the sessions that a regular user is currently having (roughly cookies). I was thinking if it was possible to spawn a 'fraudster' from a 'regular user' because at that moment I have easy access to that data. Does that make sense?

Does anybody have other options? I think sharing data between different users is difficult? It'll probably be difficult to not slow down 'threads' (I don't think they're real threads) with locking etc.

Once again: I'm not a Python/Locust expert by any means.

[cyberw]

Hmm... Is the "fraud user" just a new TCP/HTTP connection with stolen cookies?

If so, it's entirely possible to do, but not exactly trivial. You can access the individual cookies and add them to a second, newly connected Session object.

If the fraud user is always tied to a single "real" user, I wouldnt bother creating an extra user/greenlet.

If you're using FastHttpUser you can access individual cookies you can access them like this (HttpUser is probably only slightly different, but I dont have an example at hand):

                for cookie in self.client.client.cookiejar:
                    if cookie.name == "the-cookie-youre-looking-for":
                         ...

[aukevanleeuwen]

Hmm... Is the "fraud user" just a new TCP/HTTP connection with stolen cookies?

Yes, but also other state like a different User-Agent / client IP / ja4 fingerprint or whatever.

If so, it's entirely possible to do, but not exactly trivial. You can access the individual cookies and add them to a second, newly connected Session object.

If the fraud user is always tied to a single "real" user, I wouldnt bother creating an extra user/greenlet.

It depends a bit on how difficult I want to make it / how much it should look like the real world. But probably for the time being it's tied to a single user if that's easier.

If you're using FastHttpUser you can access individual cookies you can access them like this (HttpUser is probably only slightly different, but I dont have an example at hand):

                for cookie in self.client.client.cookiejar:
                    if cookie.name == "the-cookie-youre-looking-for":
                         ...

I'll probably keep it easy for now then. But if you have a pointer somewhere about how to do the non-trivial thing (maybe a test or something in the code base that you know of) I can have it in the back of my mind to chew on it for a while :-)

Thanks for your quick responses.

[cyberw]

Here's an example of how to maintain a second client in the same User instance: https://github.com/locustio/locust/blob/f3f2985f4b8783448eba3e8e85078b873aab30ea/examples/multiple_hosts.py

Probably you wouldnt need it, but if you must have actual concurrency within the same User, here's an example: https://docs.locust.io/en/latest/increase-performance.html#concurrency (these are using the same session, but you might be able to combine the two approaches)

I think actually creating a full User inside another one is not a good idea :)