Tunes the initial size of various reusable ArrayLists to reduce required growth when processing real-world data. #1048
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…red growth when processing real-world data.
jobarr-amzn
approved these changes
Feb 11, 2025
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I think it would be helpful to add comments which lead to how this was tuned/chosen. Perhaps that's redundant, please feel free to take or leave at your discretion. I just note that the commit says "tune" but doesn't describe how these numbers were selected. The PR description/thread can at least be added to later so that indirection is useful.
| @@ -1221,7 +1221,7 @@ private class EncodingDirectiveReader { | |||
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| boolean isSymbolTableAppend = false; | |||
| boolean isMacroTableAppend = false; | |||
| List<String> newSymbols = new ArrayList<>(8); | |||
| List<String> newSymbols = new ArrayList<>(128); | |||
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Suggested change
| List<String> newSymbols = new ArrayList<>(128); | |
| List<String> newSymbols = new ArrayList<>(128); // ion-java #1048 |
| @@ -25,7 +25,7 @@ public abstract class EExpressionArgsReader { | |||
| private final ReaderAdapter reader; | |||
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| // Reusable sink for expressions. | |||
| protected final List<Expression.EExpressionBodyExpression> expressions = new ArrayList<>(16); | |||
| protected final List<Expression.EExpressionBodyExpression> expressions = new ArrayList<>(128); | |||
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Suggested change
| protected final List<Expression.EExpressionBodyExpression> expressions = new ArrayList<>(128); | |
| protected final List<Expression.EExpressionBodyExpression> expressions = new ArrayList<>(128); // ion-java #1048 |
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| private val signature: MutableList<Macro.Parameter> = ArrayList(16) | ||
| private val expressions: MutableList<TemplateBodyExpression> = ArrayList(64) |
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Suggested change
| private val signature: MutableList<Macro.Parameter> = ArrayList(16) | |
| private val expressions: MutableList<TemplateBodyExpression> = ArrayList(64) | |
| private val signature: MutableList<Macro.Parameter> = ArrayList(16) // ion-java #1048 | |
| private val expressions: MutableList<TemplateBodyExpression> = ArrayList(64) // ion-java #1048 |
| @@ -55,7 +55,7 @@ class MacroEvaluator { | |||
| /** Pool of [Expression] to minimize allocation and garbage collection. */ | |||
| val expressionPool: PooledExpressionFactory = PooledExpressionFactory() | |||
| /** Pool of [ExpansionInfo] to minimize allocation and garbage collection. */ | |||
| private val expanderPool: ArrayList<ExpansionInfo> = ArrayList(32) | |||
| private val expanderPool: ArrayList<ExpansionInfo> = ArrayList(64) | |||
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Suggested change
| private val expanderPool: ArrayList<ExpansionInfo> = ArrayList(64) | |
| private val expanderPool: ArrayList<ExpansionInfo> = ArrayList(64) // ion-java #1048 |
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Description of changes:
Growing each of these arrays was the number 4 contributor to allocation rate in profiles of real-world data. We can continue to tune these values as we profile a larger corpus of data, but these are the best ones we have right now.
Speed: 216 ms/op -> 215 ms/op (~0%)
Allocation rate: 110 KB/op -> 107 KB/op (-2.7%)
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.