100% CPU usage in CryptoStore::get_user_identity

[ndren]

Steps to reproduce

Somewhat frequently Element starts spending a large amount of CPU cycles in the background. It seems that it relates to CryptoStore::get_user_identity.

Outcome

Reproduction is somewhat inconsistent, but generally going to Element then switching to a different tab will do the trick.

Firefox Profiler output: https://share.firefox.dev/42C6quy

Operating system

Arch Linux

Browser information

Firefox 137.0.2

URL for webapp

N/A

Application version

1.11.97, Rust SDK 0.10.0 (3cc301d), Vodozemac 0.9.0

Homeserver

N/A

Will you send logs?

No

[t3chguy]

@ndren that entire stack trace is in a different project, I suggest opening an issue in https://github.com/matrix-org/matrix-rust-sdk-crypto-wasm/ - cannot transfer to a different org

[richvdh]

Reopening this so that we have a tracker for the user-visible problem.

[richvdh]

@ndren I've not been able to reproduce this, nor can I see any obvious reason it might happen.

When it happens, does the tab lock up completely, or is it still somewhat responsive? If the latter, could you send debug logs (Settings -> Help & About -> Submit debug logs)?

[ndren]

Thanks for the update @richvdh. I found a cleaner reproduction now that works way more consistently:

1. Join a few Matrix spaces (in my case, with different homeservers, maybe important?)
2. Quickly click/go to different spaces
3. Notice this CPU spike occurs, longer with a higher number of spaces clicked on
   Maybe the information could be cached or the code path does not compile well to WASM?

(Off-topic: is there a standard way to submit a rageshake if I'm on an Element instance without the rageshake server?)

[richvdh]

Thanks. Do those reproduction steps result in a similar performance profile? They don't produce a cpu spike for me.

I think what's happening here is that Element-Web makes lots of calls to getUserVerificationStatus (which in turn calls CryptoStore::get_user_identity), and it's just not that efficient. It's not that bad for me, but maybe my CPU is faster.