electrs logs report "less efficient method of querying" electrs server

[Overtorment]

We have an issue: BlueWallet/BlueWallet#4336

Probably electrs wants us to always connect, keep connection alive and subscribe to all scripthashes we are interested in.
In BW we dont subscribe, as user sessions might be very short, so we try our best to quickly connect, query about scripthashes, and then dont care if user terminates the app or connection closes (which happens when user suspends the app on iOS. OS simply closes all sockets of suspended apps)

[Kixunil]

I guess ignore the warning then?

Anyway, may be interesting if we had some alternative notification mechanism so that electrs could wake up the app (e.g. by POSTing to some notification server). This would require extending the protocol and maybe even authentication. What do you think @romanz?

[romanz]

I prefer to refactor the code so the index-related functionality will be in a seprarate crate from the RPC-related functionality.
Then, it would be possible replace the whole Electrum RPC with something more REST-like, similar to how it's done in https://github.com/bwt-dev/bwt/blob/5f92c4717bdc474302305823dcf60fd3425ba8c0/src/webhooks.rs#L27.

[niteshbalusu11]

Is there a timeline on when this will be worked upon?
Right now I'm facing an issue, if I import a wallet into BlueWallet that has a long history of past transactions and try to refresh the list, electrs sometimes crashes with a long list of this error in the logs.

[caheredia]

I'm seeing the same logs with Sparrow wallet

[crcastle]

I'm getting many log messages reporting this while using Liana wallet. I opened an issue with Liana so they are aware they are using a "less efficient method of querying" electrs: wizardsardine/liana#1574

It looks like Liana uses the bdk client library and that project knows of this issue

• Use srcipthash_subscribe when syncing ElectrumBlockchain bitcoindevkit/bdk_wallet#184
• Subscribe to script hashes when using electrum client bitcoindevkit/bdk_wallet#141

But I'm getting thousands of these log messages from electrs with Liana open for an hour or so. Not a major issue, but it might be nice to rate limit that log message to keep the duplicate log lines from making it difficult to find or notice other log messages.