The following test failed in the JDK18 CI with UT enabled:

gc/g1/TestMixedGCLiveThreshold.java

Here's a snippet from the log file:

----------System.out:(6/3818)----------
Command line: [/opt/mach5/mesos/work_dir/jib-master/install/jdk-18+7-263/linux-x64.jdk/jdk-18/bin/java -cp /opt/mach5/mesos/work_dir/slaves/28992c6d-c35d-42fa-8099-898223bf183b-S25547/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f3ccbd68-37b8-4534-9618-024be2979476/runs/3e3deb6b-ada1-46b7-8b19-8c22ffe20086/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_gc/classes/3/gc/g1/TestMixedGCLiveThreshold.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-18+7-263/src.full/open/test/hotspot/jtreg/gc/g1:/opt/mach5/mesos/work_dir/slaves/28992c6d-c35d-42fa-8099-898223bf183b-S25547/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f3ccbd68-37b8-4534-9618-024be2979476/runs/3e3deb6b-ada1-46b7-8b19-8c22ffe20086/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_gc/classes/3/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/javatest.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/jtreg.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/junit.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/hamcrest.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/testng.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/jcommander.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/guice.jar -Xbootclasspath/a:. -XX:+UseG1GC -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+WhiteBoxAPI -Xlog:gc+remset+tracking=trace -Xms10M -Xmx10M -XX:G1MixedGCLiveThresholdPercent=0 gc.g1.TestMixedGCLiveThreshold$GCTest ]
[2021-07-17T02:08:50.035322948Z] Gathering output for process 16410
[2021-07-17T02:08:51.228069318Z] Waiting for completion for process 16410
[2021-07-17T02:08:51.228169688Z] Waiting for completion finished for process 16410
Command line: [/opt/mach5/mesos/work_dir/jib-master/install/jdk-18+7-263/linux-x64.jdk/jdk-18/bin/java -cp /opt/mach5/mesos/work_dir/slaves/28992c6d-c35d-42fa-8099-898223bf183b-S25547/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f3ccbd68-37b8-4534-9618-024be2979476/runs/3e3deb6b-ada1-46b7-8b19-8c22ffe20086/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_gc/classes/3/gc/g1/TestMixedGCLiveThreshold.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-18+7-263/src.full/open/test/hotspot/jtreg/gc/g1:/opt/mach5/mesos/work_dir/slaves/28992c6d-c35d-42fa-8099-898223bf183b-S25547/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f3ccbd68-37b8-4534-9618-024be2979476/runs/3e3deb6b-ada1-46b7-8b19-8c22ffe20086/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_gc/classes/3/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/javatest.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/jtreg.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/junit.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/hamcrest.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/testng.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/jcommander.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/6/1/bundles/jtreg-6+1.zip/jtreg/lib/guice.jar -Xbootclasspath/a:. -XX:+UseG1GC -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+WhiteBoxAPI -Xlog:gc+remset+tracking=trace -Xms10M -Xmx10M -XX:G1MixedGCLiveThresholdPercent=25 gc.g1.TestMixedGCLiveThreshold$GCTest ]
[2021-07-17T02:08:51.229628071Z] Gathering output for process 16495
----------System.err:(15/1043)----------
java.lang.RuntimeException: Regions selected for rebuild. G1MixedGCLiveThresholdPercent=25 no regions should be selected: expected true to equal false
at jdk.test.lib.Asserts.fail(Asserts.java:594)
at jdk.test.lib.Asserts.assertEquals(Asserts.java:205)
at gc.g1.TestMixedGCLiveThreshold.testMixedGCLiveThresholdPercent(TestMixedGCLiveThreshold.java:66)
at gc.g1.TestMixedGCLiveThreshold.main(TestMixedGCLiveThreshold.java:55)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:312)
at java.base/java.lang.Thread.run(Thread.java:833)

JavaTest Message: Test threw exception: java.lang.RuntimeException
JavaTest Message: shutting down test

result: Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: Regions selected for rebuild. G1MixedGCLiveThresholdPercent=25 no regions should be selected: expected true to equal false