Github user jbertram commented on a diff in the pull request: https://github.com/apache/activemq-artemis/pull/2228#discussion_r208790685 --- Diff: artemis-selector/src/main/java/org/apache/activemq/artemis/selector/impl/SelectorParser.java --- @@ -80,11 +78,15 @@ public static BooleanExpression parse(String sql) throws FilterException { StrictParser parser = new StrictParser(new StringReader(actual)); e = parser.JmsSelector(); } - cache.put(sql, e); + synchronized (cache) { --- End diff -- My guess is that the LRUCache is there mainly because it was used in Apollo and basically the whole selector implementation from Apollo was ported over to the Artemis code-base during the Apache donation process. It is a simple mitigation against excessive parsing, but perhaps it is premature optimization as well. I don't see a big problem with pulling it out. It would simplify the code-base a bit and eliminate the threading problem as well. I certainly don't see any reason to invest resources into a more robust/elegant/higher-performance cache implementation.
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