HTTP Metrics Performance with MPMetrics

[jdmcclur]

I see a performance issue with HTTP Metrics related to recording the metrics when MPMetrics is enabled. This is with a simple primitive test hitting a very simple REST endpoint, so overheads are exaggerated to what someone would see in a "normal" application. This is a follow on to #29396.

There are a few areas to investigate. but most of the overhead is from the LegacyMetricregistryAdapter

  Parent      0   0.10  11.77           5         585    J:io/openliberty/microprofile/metrics50/http/MPMetricsHTTPMetricsAdapterImpl.updateHttpMetrics(Lio/openliberty/http/monitor/HttpStatAttributes;Ljava/time/Duration;)V
 
    Self      0   0.10  11.77           5         585    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.timer(Lorg/eclipse/microprofile/metrics/Metadata;[Lorg/eclipse/microprofile/metrics/Tag;)Lorg/eclipse/microprofile/metrics/Timer;
 
   Child      0   0.22   9.48          11         471    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.internalTimer(Lio/smallrye/metrics/legacyapi/MpMetadata;Lio/smallrye/metrics/legacyapi/MetricDescriptor;)Lio/smallrye/metrics/legacyapi/TimerAdapter;
   Child      0   0.34   2.17          17         108    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.withAppTags([Lorg/eclipse/microprofile/metrics/Tag;)Lio/micrometer/core/instrument/Tags;
   Child      0   0.00   0.02           0           1    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.internalGetMetadataTimers(Lorg/eclipse/microprofile/metrics/Metadata;)Lio/smallrye/metrics/legacyapi/MpMetadata;

Mostly converting the MetricDescriptor (and all the tags I assume) to a MetricID.

  Parent      0   0.00   5.63           0         280    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.addNameToApplicationMap(Lio/smallrye/metrics/legacyapi/MetricDescriptor;)V
 
    Self      0   0.00   5.63           0         280    J:io/smallrye/metrics/legacyapi/MetricDescriptor.toMetricID()Lorg/eclipse/microprofile/metrics/MetricID;
 
   Child      0   0.04   5.63           2         280    J:io/smallrye/metrics/legacyapi/MetricDescriptor$ExtendedMetricID.<init>(Lio/smallrye/metrics/legacyapi/MetricDescriptor;)V

Which eventually gets down to the Tag.<init>

  Parent      0   0.02   4.06           1         202    J:io/smallrye/metrics/legacyapi/MetricDescriptor.lambda$convertTags$0(Ljava/util/List;Lio/micrometer/core/instrument/Tag;)V
 
    Self      0   0.02   4.06           1         202    J:org/eclipse/microprofile/metrics/Tag.<init>(Ljava/lang/String;Ljava/lang/String;)V
 
   Child      0   0.00   3.68           0         183    J:java/util/regex/Matcher.matches()Z
   Child      0   0.00   0.36           0          18    J:java/util/regex/Pattern.matcher(Ljava/lang/CharSequence;)Ljava/util/regex/Matcher;

Another area is below. I looked into updating to a newer version of Tags (#29982). It helped maybe 0.5%, but not sure it iss worth the hassle. I'll get back to this when I have time.

  Parent      0   0.34   2.17          17         108    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.timer(Lorg/eclipse/microprofile/metrics/Metadata;[Lorg/eclipse/microprofile/metrics/Tag;)Lorg/eclipse/microprofile/metrics/Timer;
 
    Self      0   0.34   2.17          17         108    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.withAppTags([Lorg/eclipse/microprofile/metrics/Tag;)Lio/micrometer/core/instrument/Tags;
 
   Child      0   0.00   1.59           0          79    J:io/micrometer/core/instrument/Tags.and(Ljava/lang/String;Ljava/lang/String;)Lio/micrometer/core/instrument/Tags;
   Child      0   0.00   0.24           0          12    J:io/smallrye/metrics/legacyapi/LegacyMetricRegistryAdapter.combineApplicationTagsWithMPConfigAppNameTag(Lio/micrometer/core/instrument/Tags;)Lio/micrometer/core/instrument/Tags;