Optimize parsing performance #135
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This optimization avoids unnecessary object allocations by not taking snapshots of the parsing state when the relevant nodes are unique.
According to JMH's JMHSamples_08_DeadCode, the correct way of benchmarking is either returning the result or consuming it with Blackholes.
intsuc
commented
Aug 11, 2023
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| final CommandContextBuilder<S> context = unique ? contextSoFar : contextSoFar.copy(); | ||
| final StringReader reader = unique ? originalReader : new StringReader(originalReader); |
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If unique, we do not need to take snapshots of the parsing state (contextSoFar and originalReader) here.
intsuc
commented
Aug 11, 2023
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| if (unique) { | ||
| return parse; | ||
| } |
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If unique, the potentials will always contain only parse and this parse will be returned after exiting this for loop, so we can return parse here without allocating potentials.
intsuc
commented
Aug 11, 2023
| if (potentials == null) { | ||
| potentials = new ArrayList<>(1); | ||
| potentials = new ArrayList<>(relevantNodes.size()); |
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Since potentials will contain ParseResults<S> up to the amount of relevantNodes.size(), allocate that capacity in advance to ensure resizing never occurs.
yanisderbikov
approved these changes
Nov 12, 2023
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I think this is less readable. But if it increase performance it's ok.
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Overview
This optimization avoids unnecessary object allocations by not taking snapshots of the parsing state when the size of the relevant nodes is
1. Parsing time becomes about 48.6 to 57.1% of the original.Benchmark Results
Before Optimization f20bede
ParsingBenchmarks.parse_ParsingBenchmarks.parse_a1iParsingBenchmarks.parse_cParsingBenchmarks.parse_k1iParsingBenchmarks.parse_l123456789After Optimization f4d27ab
ParsingBenchmarks.parse_ParsingBenchmarks.parse_a1iParsingBenchmarks.parse_cParsingBenchmarks.parse_k1iParsingBenchmarks.parse_l123456789