[#531] JFR events for allocation and resizing #532
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| public long[] readLongs(String fieldName) throws IOException { | ||
| List<Long> values = readCollection(fieldName, new ArrayList<>(), Long.class); | ||
| long[] result = new long[values.size()]; | ||
| JfrEventPublisher.bufferAllocateEvent(result.length * Long.BYTES); |
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I am most likely micro-optimizing, but if JFR is disabled, you're still doing unnecessary multiplications. WOuldn't it be better to have bufferAllocateLong, bufferAllocateInteger, etc methods instead and do the multiplication only inside the if statement?
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That sounds good. Let me update.
jabolina
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@jabolina Did you find using this showed anything interesting? I wonder how easy it is to parse this type of information. |
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Let me put together a script with JBang to extract the values and generate a summary of sorts. The only thing I've noticed is that it emits so many events that it can hurt perf badly, so it is something to have enabled only for analysis, at most. 
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* Requires JFR package. * Covering read and write path.
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Ok, I've pushed a small script to generate a summary: |
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I think it might be useful to put the script somewhere. My only complaint is technically don't we have this with JFR/async profiler when tracking allocations? I am trying to think when I would use this over that. |
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I see. I think allocation with JFR/async-profiler would be generalized to the whole JVM. You should then be able to filter out when generating the flamegraph. I guess the flamegraph would be larger in places where it has more allocations? I am not sure if it exposes the allocation size (you can set a minimum size in asprof). And it wouldn't distinguish between allocating or resizing a buffer either. All in all, I guess this provides a little more specific info. |
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Closes #531.