The current implementation of TicketHolder::resize resizes the pool by adding or removing tickets one by one in a loop. This is acceptable for code like execution control, which changes the pool size by small increments and needs to wait until the concurrency level is actually at the new value. It's not acceptable for code like ingress admission control, which might need to resize the pool from 1 million tickets down to a few hundreds and would need this resize to take effect as quickly as possible.