During fast_match, drain always iterates over all possible clusters and updates their access time in the cache. This leads to two problems:

• The update slows down the performance
• Even clusters that will never match anymore will never be removed from cache

Expected behavior:

Cluster will only be updated/touched in cache after they were actual used/chosen. There is actually a comment for this in the source code already:

Try to retrieve cluster from cache with bypassing eviction algorithm as we are only testing candidates for a match.
https://github.com/IBM/Drain3/blob/15470e391caed9a9ef5038cdd1dbd373bd2386a8/drain3/drain.py#L217