"Bat Ledger Service" causing 100% CPU usage

Description

We’ve been receiving several reports from our users that Bat Ledger Service causes the CPU to increase to 100% in some cases in 1.5.x which causes performance issues. We’ve had a similar issue in 1.7.x and 1.8.x that we resolved via https://github.com/brave/brave-browser/issues/8691. However, this issue has been reported on 1.3.x, 1.4.x and 1.5.x so it’s a different problem.

@NejcZdovc has been debugging the issue a user and mentioned that the CPU dropped from 100% once the ballets object in ledger_state was removed.

Some links to users experiencing this issue:

• https://github.com/brave/brave-browser/issues/8779#issuecomment-602736059
• https://twitter.com/bvaivoda/status/1241240604257873921

There’s other reports via https://community.brave.com regarding high CPU usage even after https://github.com/brave/brave-browser/issues/8691 and https://github.com/brave/brave-browser/issues/8779 have been fixed.

Steps to Reproduce

• N/A (currently we don’t really have any STR as @NejcZdovc still investigating)

Actual result:

Expected result:

“Bat Ledger Service” shouldn’t be using 100% of the CPU.

Reproduces how often:

• N/A (we still don’t know enough information but there’s some users experiencing this)

Brave version (brave://version info)

• This has been reported on 1.3.x, 1.4.x and the latest 1.5.x. Assuming it’s an issue on every channel and separate from https://github.com/brave/brave-browser/issues/8691.

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes, received reports from 1.5.x
• Can you reproduce this issue with the beta channel? Most likely also affected
• Can you reproduce this issue with the dev channel? Most likely also affected
• Can you reproduce this issue with the nightly channel? Most likely also affected

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? N/A
• Does the issue resolve itself when disabling Brave Rewards? Most likely would resolve the issue
• Is the issue reproducible on the latest version of Chrome? N/A

Miscellaneous Information:

CCing @NejcZdovc @mandar-brave @bsclifton @rebron @jsecretan

[SephReed]

Still broken

Could you guys please add a feature do disable “Bat Ledger Service.” I’d like to have my browser be usable again, and I don’t care about losing BAT features to make that happen.

[NejcZdovc]

@MinisterFister this is not related to db migration. It’s operation that process publisher list. It normally takes 30s to complete. We are working on new mechanism that will solve it