Describe the bug
G1 Old Memory leaking when using the javaagent with tracing and otel.exporter.otlp.protocol=grpc under load. I created this issue here because the ProtoSerializer is the leak suspect as also seen in #7083 #7083.

Edit 1: Updating the #7083 reference to point to the right opentelemetry-java GH issue.

Steps to reproduce

1. Using a maven-version of the javaagent example
2. Attaching the javaagent with the following parameters (leaky-1.0-SNAPSHOT.jar is the javaagent example jar):

SERVER_PORT=8080 java -Dfile.encoding=UTF-8 -Xms1024m -Xmx1024m -XX:MaxMetaspaceSize=256m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=heapdump.hprof -javaagent:opentelemetry-javaagent.jar -Dotel.service.name=leaky -Dotel.resource.attributes=service.instance.id=grpc -Dotel.instrumentation.common.default-enabled=true -Dotel.metric.export.interval=200 -Dotel.logs.exporter=none -Dotel.exporter.otlp.protocol=grpc -jar target/leaky-1.0-SNAPSHOT.jar

3. Running simple load-test (k6) against the service:

import http from 'k6/http';

export const options = {
  scenarios: {
    hello: {
      executor: 'constant-vus',
      vus: 100,
      duration: '240m',
    },
  },
  noConnectionReuse: true,
};

export default function () {
  const response = http.get(`http://localhost:${__ENV.SERVER_PORT}/ping`);
}

What did you see?
When executing the k6 tests for ~3 hours, we see an ever-increasing heap G1 Old memory that leads eventually to java.lang.OutOfMemoryError:

What did you expect to see?
Constant G1 Old heap memory.

What version and what artifacts are you using?
Artifacts: opentelemtry-javaagent=2.21.0, opentelemetry-sdk=1.55.0
How did you reference these artifacts? (excerpt from your build.gradle, pom.xml, etc)

# pom.xml
<dependency>
  <groupId>io.opentelemetry</groupId>
  <artifactId>opentelemetry-sdk</artifactId>
  <version>1.55.0</version>
  <scope>compile</scope>
</dependency>

Environment
Compiler: openjdk 17.0.2
OS: Apple M2 Pro
Note: The original memory leak was seen in our production systems, but I wanted to provide a "reproduction" case that can be run locally.

Additional context
Using otel.exporter.otlp.protocol=http/protobuf in the javaagent did not show signs of any memory leakage in the G1 Old heap memory.

Edit 2: Forgot to mention that I can provide the heapdump.hprof via email, I did not include it because there is a limit on the size of zip files in GH.