Improving Qute Escaper to be as branch-free as possible

[franz1981]

This is a show case of the approach at lemire/Code-used-on-Daniel-Lemire-s-blog#116 but biased for the one and two replacement latin chars case.
It could be expanded to cover for non-latin and the 6 bytes replacement too, with more painfull and complex (in term of logic) changes - but it looks already complex as it is IMO.

Feedbacks are wellcome as questions.
I didn't yet benchmarked it (is sadly low in my prio list - so IDK when I'll have time to contribute a proper bench which stress the branch-predictor in qute-benchmark) - and there's a good chance my "bet" to use StringBuilder to simplify it, making use of the horrible setLength in the hot path, won't pay off.
In such unfortunate case, I will move to using char[] despite it requires latinness checks due to compact string, on String construction :"(

[franz1981]

Using the benchmark at mkouba/qute-benchmarks#1

shows these differences in perf - now:

Benchmark                   (ctrlProbabibility)  (latinCharsProbability)  (replacementProbability)  (samples)  (size)  Mode  Cnt   Score   Error  Units
JsonEscaping.escape                           0                      100                         0        100      32  avgt   10  10.129 ± 0.009  ns/op
JsonEscaping.escape                           0                      100                         0      10000      32  avgt   10  10.129 ± 0.038  ns/op
JsonEscaping.escape                           0                      100                        10        100      32  avgt   10  45.312 ± 0.193  ns/op
JsonEscaping.escape                           0                      100                        10      10000      32  avgt   10  55.989 ± 1.826  ns/op
JsonEscaping.escape                          10                      100                        10        100      32  avgt   10  44.131 ± 2.367  ns/op
JsonEscaping.escape                          10                      100                        10      10000      32  avgt   10  77.187 ± 2.496  ns/op

vs before

Benchmark            (ctrlProbabibility)  (latinCharsProbability)  (replacementProbability)  (samples)  (size)  Mode  Cnt    Score    Error  Units
JsonEscaping.escape                    0                      100                         0        100      32  avgt   10   16.864 ±  0.514  ns/op
JsonEscaping.escape                    0                      100                         0      10000      32  avgt   10   66.942 ±  0.524  ns/op
JsonEscaping.escape                    0                      100                        10        100      32  avgt   10   97.493 ±  5.357  ns/op
JsonEscaping.escape                    0                      100                        10      10000      32  avgt   10  220.471 ±  7.429  ns/op
JsonEscaping.escape                   10                      100                        10        100      32  avgt   10  178.098 ± 15.693  ns/op
JsonEscaping.escape                   10                      100                        10      10000      32  avgt   10  319.793 ± 40.863  ns/op

which is a good improvement - which tends to pay-off more as the number of chars increases

Fyi @mkouba the relevant ones are using 10000 samples since with just 100 the data are very predictable for my CPU model and you cannot really see the benefits of reducing the number of branches

[franz1981]

@galderz on mkouba/qute-benchmarks#1

this implementation should really shine with native image, since it doesn't use StringBuilder :)

[mkouba]

Using the benchmark at mkouba/qute-benchmarks#1

I had to rewrite the JsonEscaping benchmark so that it's using a template instead of JsonEscaper because this class was only introduced in 3.18 and we need to compile/run benchmarks for older versions as well...

shows these differences in perf with before:

Benchmark                   (ctrlProbabibility)  (latinCharsProbability)  (replacementProbability)  (samples)  (size)  Mode  Cnt   Score   Error  Units
JsonEscaping.escape                           0                      100                         0        100      32  avgt   10  10.129 ± 0.009  ns/op
JsonEscaping.escape                           0                      100                         0      10000      32  avgt   10  10.129 ± 0.038  ns/op
JsonEscaping.escape                           0                      100                        10        100      32  avgt   10  45.312 ± 0.193  ns/op
JsonEscaping.escape                           0                      100                        10      10000      32  avgt   10  55.989 ± 1.826  ns/op
JsonEscaping.escape                          10                      100                        10        100      32  avgt   10  44.131 ± 2.367  ns/op
JsonEscaping.escape                          10                      100                        10      10000      32  avgt   10  77.187 ± 2.496  ns/op

vs 7ec85cc

Benchmark            (ctrlProbabibility)  (latinCharsProbability)  (replacementProbability)  (samples)  (size)  Mode  Cnt    Score    Error  Units
JsonEscaping.escape                    0                      100                         0        100      32  avgt   10   16.864 ±  0.514  ns/op
JsonEscaping.escape                    0                      100                         0      10000      32  avgt   10   66.942 ±  0.524  ns/op
JsonEscaping.escape                    0                      100                        10        100      32  avgt   10   97.493 ±  5.357  ns/op
JsonEscaping.escape                    0                      100                        10      10000      32  avgt   10  220.471 ±  7.429  ns/op
JsonEscaping.escape                   10                      100                        10        100      32  avgt   10  178.098 ± 15.693  ns/op
JsonEscaping.escape                   10                      100                        10      10000      32  avgt   10  319.793 ± 40.863  ns/op

which is a good improvement - which tends to pay-off more as the number of chars increases

Aren't those numbers swapped given the fact that avgt mode is used (average time per per operation - lower is better)?

Fyi @mkouba the relevant ones are using 10000 samples since with just 100 the data are very predictable for my CPU model and you cannot really see the benefits of reducing the number of branches

Ok 👍

[franz1981]

using a template instead of JsonEscaper

Numbers still look the same? Did you checked 🙏?

Aren't those numbers swapped given the fact that avgt mode is used (average time per per operation - lower is better)?

Ops 🤣 I copied in the wrong order , let me fix it

[franz1981]

The HTML one can still made faster, working on it

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[franz1981]

The doc here is not up to date with the latest changes..I ended up accepting having a slightly bigger footprint, but better latency

[quarkus-bot]

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This is the status report for running Quarkus CI on commit 1939891.

Failing Jobs

Status	Name	Step	Failures	Logs	Raw logs	Build scan
✖	Native Tests - Misc4	Build	Failures	Logs	Raw logs	🔍

Full information is available in the Build summary check run.
You can consult the Develocity build scans.

Failures

⚙️ Native Tests - Misc4 #

- Failing: integration-tests/observability-lgtm 

📦 integration-tests/observability-lgtm

✖ io.quarkus.observability.test.LgtmResourcesIT.testTracing - History - More details - Source on GitHub

java.lang.RuntimeException: 
java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step io.quarkus.observability.deployment.ObservabilityDevServiceProcessor#startContainers threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/grafana/otel-lgtm:0.8.2
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.lambda$startContainers$3(ObservabilityDevServiceProcessor.java:170)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.startContainers(ObservabilityDevServiceProcessor.java:113)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:732)

---

Flaky tests - Develocity

⚙️ JVM Tests - JDK 17

📦 integration-tests/observability-lgtm

✖ io.quarkus.observability.test.LgtmServicesTest.testTracing - History

• java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors [error]: Build step io.quarkus.observability.deployment.ObservabilityDevServiceProcessor\#startContainers threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/grafana/otel-lgtm:0.8.2 at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.lambda$startContainers$3(ObservabilityDevServiceProcessor.java:170) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) - java.lang.RuntimeException

java.lang.RuntimeException: 
java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step io.quarkus.observability.deployment.ObservabilityDevServiceProcessor#startContainers threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/grafana/otel-lgtm:0.8.2
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.lambda$startContainers$3(ObservabilityDevServiceProcessor.java:170)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.startContainers(ObservabilityDevServiceProcessor.java:113)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:732)

---

⚙️ JVM Tests - JDK 21

📦 integration-tests/observability-lgtm

✖ io.quarkus.observability.test.LgtmReloadTest.testReload - History

• io.quarkus.builder.BuildException: Build failure: Build failed due to errors [error]: Build step io.quarkus.observability.deployment.ObservabilityDevServiceProcessor\#startContainers threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/grafana/otel-lgtm:0.8.2 at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.lambda$startContainers$3(ObservabilityDevServiceProcessor.java:170) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1708) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) - java.lang.RuntimeException

java.lang.RuntimeException: 
io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step io.quarkus.observability.deployment.ObservabilityDevServiceProcessor#startContainers threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/grafana/otel-lgtm:0.8.2
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.lambda$startContainers$3(ObservabilityDevServiceProcessor.java:170)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1708)
	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
	at io.quarkus.observability.deployment.ObservabilityDevServiceProcessor.startContainers(ObservabilityDevServiceProcessor.java:113)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)