Fix inacccurate memory metric due to concurrent writes

[asdacap]

• Because the commit is now concurrent, the memory used mettrics need to be modified atomically.
• Because it was not atomically modified, it use more memory than tracked causing unintended increased pruning interval.

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No