[Skylark] Avoid unnecessary copyOf invocations. #5699
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ttsugriy
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dkelmer,
dslomov,
laurentlb and
vladmos
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I'm a bit surprised by this change. I thought |
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@laurentlb, I thought so too, but according to source that's not the case :( |
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just to be clear - there are no allocations involved in |
| @@ -319,7 +319,7 @@ public static boolean toBoolean(Object o) { | |||
| for (Map.Entry<?, ?> entries : dict.entrySet()) { | |||
| list.add(entries.getKey()); | |||
| } | |||
| return ImmutableList.copyOf(list); | |||
| return ImmutableList.copyOf(list); | |||
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Random driveby while skimming the PR & seeing the whitespace bump on this line: Convert this over to an ImmutableList.builderWithExpectedSize() also?
It presumably isn't getting called much if your numbers didn't complain about it too, but it's making an ArrayList only to have ImmutableList immediately copy it all.
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Good catch, @deadmoose! I'm gradually going through all of them, but before I'm trying to use either JMH or async-profiler to see the impact, so it's a bit slow :) I'll shoot a PR with this change as soon as I confirm in JMH that it makes things faster. Most likely your suggestion should improve things, since my previous testing showed that ImmutableList.builder + build is interestingly faster than ArrayList.add, but I'll double check.
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Looks good! Can you add a comment to the function to explain why it was added? |
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Thanks for taking a look, @laurentlb! I'll add a comment. |
Java uses dynamically generated proxy classes to access annotation properties and their methods are ~7X slower than plain getters. According to async-profiler 50%+ of `convertArgumentList` method time is spent in dynamic proxy methods, so optimizing their performance makes sense. This also makes the model less anemic, since POJOs can actually provide business methods.
This change is focused on 2 things: - avoid creating builders in case they don't end up being used - create builders using the maximum expected size to avoid intermediate allocations to accomodate more elements
Java uses dynamically generated proxy classes to access annotation properties and their methods are ~7X slower than plain getters. According to async-profiler 50%+ of `convertArgumentList` method time is spent in dynamic proxy methods, so optimizing their performance makes sense. This also makes the model less anemic, since POJOs can actually provide business methods.
According to async-profiler, about 50% of `Tuple.getSlice` method invocation is spent in `ImmutableList.copyOf` which is completely unnecessary for cases when an `ImmutableList` instance is passed.
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rebased, resolved conflicts and added a comment |
According to async-profiler, about 50% of
Tuple.getSlicemethod invocation is spent inImmutableList.copyOfwhich is completely unnecessary for cases when anImmutableListinstance is passed.