[GitHub] [jena] Aklakan opened a new issue, #1474: PrefixMapStd is very slow for lookups that 'miss'

[GitBox <gi...@apache.org>]

Aklakan opened a new issue, #1474:
URL: https://github.com/apache/jena/issues/1474

   ### Version
   
   4.6.0-SNAPSHOT
   
   ### What happened?
   
   Another follow up on https://issues.apache.org/jira/browse/JENA-2309
   I investigated the issue of slow PrefixMapStd further and it turns out that when there are 'hits' using it's fast track approach its very fast - however on 'misses' it gets extremely slow because then it falls back to iteration of all prefixes in the map.
   
   Using a small benchmark runner (part of the PR) shows the the PrefixMap can be easily brought to require dozens of seconds for lookups that can be accomplished in a split second.
   For that I created a new PrefixMap intended as a replacement that combines the best of both worlds: The fast track of PrefixMapStd and the trie backing (together with a guava cache) of the removed FastAbbreviatingPrefixMap.
   
   Approach 0 = Jena's original PrefixMapStd:
   ```
   Run 1 with base <http://example.org/> and separator / using approach 0: Static IRI lookups took 0.082 seconds
   Run 1 with base <http://example.org/> and separator / using approach 0: Dynamic IRI lookups took 33.443 seconds
   Run 1 with base <urn:foo:bar:> and separator : using approach 0: Static IRI lookups took 25.482 seconds
   Run 1 with base <urn:foo:bar:> and separator : using approach 0: Dynamic IRI lookups took 31.088 seconds
   ```
   
   Approach 1 = my optimized PrefixMap:
   ```
   Run 1 with base <http://example.org/> and separator / using approach 1: Static IRI lookups took 0.070 seconds
   Run 1 with base <http://example.org/> and separator / using approach 1: Dynamic IRI lookups took 0.401 seconds
   Run 1 with base <urn:foo:bar:> and separator : using approach 1: Static IRI lookups took 0.099 seconds
   Run 1 with base <urn:foo:bar:> and separator : using approach 1: Dynamic IRI lookups took 0.433 seconds
   ```
   
   
   
   ### Relevant output and stacktrace
   
   _No response_
   
   ### Are you interested in making a pull request?
   
   Yes


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