ConnectionReuseTest FAILED in Test_openjdk11_hs_extended.openjdk_s390x_linux

**Failing Test Info**
Test Name: java/net/httpclient/http2/ConnectionReuseTest.java
Test Duration: 6.5 seconds
Machine it fails on: [test-marist-ubuntu2404-s390x-1](https://ci.adoptium.net/computer/test-marist-ubuntu2404-s390x-1)
Machines it passes on (if intermittent): [test-docker-ubuntu2404-s390x-1](https://ci.adoptium.net/computer/test-docker-ubuntu2404-s390x-1) [test-docker-sles15-s390x-1](https://ci.adoptium.net/computer/test-docker-sles15-s390x-1)
Confirmed: Can passes and fail on the same machine. Grinder passes, but named job can fail.

**Jenkins Test Job Info**
Jenkins Test Job Name: Test_openjdk11_hs_extended.openjdk_s390x_linux_testList_6
Jenkins Test Job URL: https://ci.adoptium.net/job/Test_openjdk11_hs_extended.openjdk_s390x_linux_testList_6/35/
TRSS link for the build (if available): https://trss.adoptium.net/allTestsInfo?buildId=698939ca928502006ed0cc13&limit=1

**Deep History Link from TRSS (if available)**

https://trss.adoptium.net/deepHistory?testId=69893d6d928502006ed0f057

** Rerun in Grinder Link (if available) or Steps to Reproduce**

[Grinder link.](https://ci.adoptium.net/job/Grinder/parambuild/?SDK_RESOURCE=upstream&TARGET=jdk_custom&BASE_DOCKER_REGISTRY_CREDENTIAL_ID=&TEST_FLAG=&UPSTREAM_TEST_JOB_NAME=Test_openjdk11_hs_extended.openjdk_s390x_linux&DOCKER_REQUIRED=false&ACTIVE_NODE_TIMEOUT=5&VENDOR_TEST_DIRS=&EXTRA_DOCKER_ARGS=&TKG_OWNER_BRANCH=adoptium%3Amaster&OPENJ9_SYSTEMTEST_OWNER_BRANCH=eclipse%3Amaster&PLATFORM=s390x_linux&GENERATE_JOBS=true&KEEP_REPORTDIR=true&PERSONAL_BUILD=false&DOCKER_REGISTRY_DIR=&RERUN_ITERATIONS=0&ADOPTOPENJDK_REPO=https%3A%2F%2Fgithub.com%2Fadoptium%2Faqa-tests.git&SETUP_JCK_RUN=false&DOCKER_REGISTRY_URL_CREDENTIAL_ID=&LABEL=&EXTRA_OPTIONS=&CUSTOMIZED_SDK_URL=&BUILD_IDENTIFIER=&JENKINS_KEY=&ADOPTOPENJDK_BRANCH=master&LIGHT_WEIGHT_CHECKOUT=false&USE_JRE=false&ARTIFACTORY_SERVER=&KEEP_WORKSPACE=false&USER_CREDENTIALS_ID=&JDK_VERSION=11&DOCKER_REGISTRY_URL=&ITERATIONS=1&VENDOR_TEST_REPOS=&JDK_REPO=https%3A%2F%2Fgithub.com%2Fadoptium%2Fjdk11u&JCK_GIT_BRANCH=master&OPENJ9_BRANCH=master&OPENJ9_SHA=&JCK_GIT_REPO=&VENDOR_TEST_BRANCHES=&UPSTREAM_JOB_NAME=build-scripts%2Fjobs%2Fjdk11u%2Fjdk11u-linux-s390x-temurin&OPENJ9_REPO=https%3A%2F%2Fgithub.com%2Feclipse-openj9%2Fopenj9.git&CLOUD_PROVIDER=&CUSTOM_TARGET=java%2Fnet%2Fhttpclient%2Fhttp2%2FConnectionReuseTest.java&VENDOR_TEST_SHAS=&JDK_BRANCH=jdk-11.0.31%2B1_adopt&LABEL_ADDITION=&ARTIFACTORY_REPO=&ARTIFACTORY_ROOT_DIR=&UPSTREAM_TEST_JOB_NUMBER=232&DOCKERIMAGE_TAG=&TEST_TIME=&JDK_IMPL=hotspot&SSH_AGENT_CREDENTIAL=&AUTO_DETECT=true&SLACK_CHANNEL=aqavit-bot&DYNAMIC_COMPILE=false&RELATED_NODES=&ADOPTOPENJDK_SYSTEMTEST_OWNER_BRANCH=adoptium%3Amaster&APPLICATION_OPTIONS=&CUSTOMIZED_SDK_URL_CREDENTIAL_ID=eclipse_temurin_bot_email_and_token&ARCHIVE_TEST_RESULTS=false&NUM_MACHINES=&OPENJDK_SHA=&TRSS_URL=&RERUN_FAILURE=false&USE_TESTENV_PROPERTIES=false&BUILD_LIST=openjdk&ADDITIONAL_ARTIFACTS_REQUIRED=&UPSTREAM_JOB_NUMBER=388&STF_OWNER_BRANCH=adoptium%3Amaster&TIME_LIMIT=25&JVM_OPTIONS=&PARALLEL=None)

**Java Version output (from console output)**

```
23:35:21 openjdk version "11.0.31-beta" 2026-04-21
23:35:21 OpenJDK Runtime Environment Temurin-11.0.31+1-202602062103 (build 11.0.31-beta+1-ea)
23:35:21 OpenJDK 64-Bit Server VM Temurin-11.0.31+1-202602062103 (build 11.0.31-beta+1-ea, mixed mode)
```

**Relevant Console Output (showing exceptions/errors/crashes)**

```
00:06:23 STDERR:
00:06:23 IPSupport - IPv4: true
00:06:23 IPSupport - IPv6: true
00:06:23 preferIPv4Stack: false
00:06:23 preferIPv6Addresses: true
00:06:23 STARTED ConnectionReuseTest::testConnReuse '[1] https://localhost:37049/'
00:06:23 java.net.ConnectException: Connection refused
00:06:23 at java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:562)
00:06:23 at java.net.http/jdk.internal.net.http.HttpClientFacade.send(HttpClientFacade.java:119)
00:06:23 at ConnectionReuseTest.testConnReuse(ConnectionReuseTest.java:147)
00:06:23 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
00:06:23 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
00:06:23 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
00:06:23 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
00:06:23 at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:727)
00:06:23 at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
00:06:23 at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
00:06:23 at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:156)
00:06:23 at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:147)
00:06:23 at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestTemplateMethod(TimeoutExtension.java:94)
00:06:23 at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(InterceptingExecutableInvoker.java:103)
00:06:23 at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.lambda$invoke$0(InterceptingExecutableInvoker.java:93)
00:06:23 at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
00:06:23 at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
00:06:23 at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
00:06:23 at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
00:06:23 at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:92)
00:06:23 at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:86)
00:06:23 at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:217)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:213)
00:06:23 at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:138)
00:06:23 at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:68)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
00:06:23 at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
00:06:23 at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:226)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:204)
00:06:23 at org.junit.jupiter.engine.descriptor.TestTemplateTestDescriptor.execute(TestTemplateTestDescriptor.java:142)
00:06:23 at org.junit.jupiter.engine.descriptor.TestTemplateTestDescriptor.lambda$execute$2(TestTemplateTestDescriptor.java:110)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
00:06:23 at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:658)
00:06:23 at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:274)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
00:06:23 at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
00:06:23 at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
00:06:23 at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
00:06:23 at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
00:06:23 at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:274)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
00:06:23 at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
00:06:23 at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
00:06:23 at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
00:06:23 at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
00:06:23 at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
00:06:23 at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:274)
00:06:23 at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
00:06:23 at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
00:06:23 at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
00:06:23 at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
00:06:23 at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
00:06:23 at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
00:06:23 at org.junit.jupiter.engine.descriptor.TestTemplateTestDescriptor.execute(TestTemplateTestDescriptor.java:110)
00:06:23 at org.junit.jupiter.engine.descriptor.TestTemplateTestDescriptor.execute(TestTemplateTestDescriptor.java:44)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
00:06:23 at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
00:06:23 at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
00:06:23 at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
00:06:23 at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
00:06:23 at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
00:06:23 at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
00:06:23 at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
00:06:23 at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
00:06:23 at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
00:06:23 at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
00:06:23 at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
00:06:23 at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:147)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:127)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:90)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:55)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:102)
00:06:23 at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:54)
00:06:23 at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
00:06:23 at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
00:06:23 at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
00:06:23 at com.sun.javatest.regtest.agent.JUnitRunner.runWithJUnitPlatform(JUnitRunner.java:142)
00:06:23 at com.sun.javatest.regtest.agent.JUnitRunner.main(JUnitRunner.java:95)
00:06:23 at com.sun.javatest.regtest.agent.JUnitRunner.main(JUnitRunner.java:61)
00:06:23 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
00:06:23 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
00:06:23 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
00:06:23 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
00:06:23 at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
00:06:23 at java.base/java.lang.Thread.run(Thread.java:829)
00:06:23 Caused by: java.net.ConnectException: Connection refused
00:06:23 at java.base/sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
00:06:23 at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:777)
00:06:23 at java.net.http/jdk.internal.net.http.PlainHttpConnection$ConnectEvent.handle(PlainHttpConnection.java:128)
00:06:23 at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.handleEvent(HttpClientImpl.java:962)
00:06:23 at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.lambda$run$3(HttpClientImpl.java:917)
00:06:23 at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
00:06:23 at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.run(HttpClientImpl.java:917)
00:06:23 FAILED ConnectionReuseTest::testConnReuse '[1] https://localhost:37049/'
```

**Attach or link to relevant artifacts**

[ConnectionReuseTest.jtr.xml](https://github.com/user-attachments/files/25209826/ConnectionReuseTest.jtr.xml)
[ConnectionReuseTest.jtr.txt](https://github.com/user-attachments/files/25209827/ConnectionReuseTest.jtr.txt)

Start with java/net/httpclient/http2/ConnectionReuseTest.java, especially the failure at line 147, then review the linked Jenkins job and TRSS deep history. Reproduce the intermittent Connection refused failure through the provided Grinder link on s390x and compare the passing and failing machine results. Done means the cause is identified and the test or test environment is verified against the failure.

Written by the indexing model from the issue text.