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Performance fixes based on hotspot analysis in load tests #11148

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Performance fixes based on hotspot analysis in load tests #11148

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37f534b
Merge pull request #1 from quarkusio/master
bcluap Aug 2, 2020
fcbab4e
Performance improvements
Aug 3, 2020
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2 changes: 1 addition & 1 deletion extensions/jaeger/runtime/src/main/java/io/quarkus/jaeger/runtime/MDCScope.java
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ public Span span() {

protected void putContext(JaegerSpanContext spanContext) {
MDC.put(TRACE_ID, spanContext.getTraceId());
MDC.put(SPAN_ID, String.format("%16x", spanContext.getSpanId()));
MDC.put(SPAN_ID, Long.toHexString(spanContext.getSpanId()));
MDC.put(SAMPLED, Boolean.toString(spanContext.isSampled()));
}
}
4 changes: 4 additions & 0 deletions ...pendent-projects/arc/runtime/src/main/java/io/quarkus/arc/impl/AbstractSharedContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,10 @@ public boolean equals(Object obj) {
return false;
}
Key other = (Key) obj;
// Shortcut removes hotspot on contextual.equals
if (contextual == other.contextual) {
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Hm, at the moment we don't implement equals()/hashCode() for generated bean classes so !contextual.equals(other.contextual) should be translated to !(contextual == other.contextual). In other words, this modification could save one java.lang.Object.equals(Object) invocation (which is very likely negligible although it removes the equals method from the hot path). Long.toHexString() saves probably a lot more because String.format() creates a formatter object, parses the string, etc.

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@mkouba what's you're saying is we should drop the equals() call altogether?

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Nope. I'd like to keep it. The fact that we don't implement it now does not mean we'll never need to implement it.

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OK. But if it ended up being a hot spot for Paul, there's something weird going on.

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It's hard to say without the app and test sources. CC @bcluap

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So, I just saw that the profiler used is the one from VisualVM, it inject some bytecode and can generates deoptimization.
That's why it can misleading you to such kind of hotspot.
When working on lowlevel optimizations (and avoiding a method call is very low level), you should use low level stuff like async-profiler, we have a page that expalain how to use it: https://github.com/quarkusio/quarkus/blob/master/TROUBLESHOOTING.md

So again, the hotspot for the equals method call is certainly a profiler artefact not a real hotspot.
And 1% difference between two load testing run is very slight so can go into the recording error range.
Such small performance enhancements should be validated via microbenchmarking using JMH ...

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Such small performance enhancements should be validated via microbenchmarking using JMH ...

Yes, we talked about this in the comments below, e.g. #11148 (comment).

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If you have many possible concrete types implementing Contextual, the dispatch to find the right equals implementation becomes a very expensive megamorphic call.
+1 for the shortcut

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As mentioned above we removed the need for equals() from the hot path completely...

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As mentioned above we removed the need for equals() from the hot path completely...

Sure that's even better. I just meant to suggest a possible explanation for the equals to be - in some contexts - really not that efficient. Removing the field is even better!

return true;
}
if (!contextual.equals(other.contextual)) {
return false;
}
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