The following test fails in the JDK15 CI:

serviceability/dcmd/gc/HeapDumpCompressedTest.java#id0

Here's a snippet from the log file:

#section:main
----------messages:(5/438)----------
command: main -XX:+UseSerialGC HeapDumpCompressedTest
reason: User specified action: run main/othervm -XX:+UseSerialGC HeapDumpCompressedTest
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules java.base,java.compiler,java.management,jdk.internal.jvmstat --add-exports java.base/jdk.internal.misc=ALL-UNNAMED --add-exports jdk.internal.jvmstat/sun.jvmstat.monitor=ALL-UNNAMED
elapsed time (seconds): 0.056
----------configuration:(5/225)----------
Boot Layer
  add modules: java.base java.compiler java.management jdk.internal.jvmstat
  add exports: java.base/jdk.internal.misc ALL-UNNAMED
               jdk.internal.jvmstat/sun.jvmstat.monitor ALL-UNNAMED

----------System.out:(2/80)----------
Error occurred during initialization of VM
Multiple garbage collectors selected
----------System.err:(0/0)----------
----------rerun:(39/6486)*----------
cd /opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/scratch/3 && \\
HOME=/tmp/sparky-temp-home-7391239903976320005/user_home \\
JDK8_HOME=/opt/mach5/mesos/work_dir/jib-master/install/jdk/14/36/bundles/linux-x64/jdk-14_linux-x64_bin.tar.gz/jdk-14 \\
JIB_DATA_DIR=/opt/mach5/mesos/work_dir/jib-master \\
JIB_HOME=/opt/mach5/mesos/work_dir/jib-master/install/com/oracle/java/jib/jib/3.0-SNAPSHOT/jib-3.0-SNAPSHOT-distribution.zip-1591722412/jib-3.0-SNAPSHOT-distribution \\
JTREG_EXTRA_PROBLEM_LISTS=ProblemList-zgc.txt \\
JTREG_KEYWORDS="!headful" \\
JTREG_VERBOSE=fail,error,time \\
LC_ALL=C \\
PATH=/bin:/usr/bin:/usr/sbin \\
TEST_IMAGE_DIR=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.test \\
TEST_IMAGE_GRAAL_DIR=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.test/hotspot/jtreg/graal \\
CLASSPATH=/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/serviceability/dcmd/gc/HeapDumpCompressedTest_id0.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg/serviceability/dcmd/gc:/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/5.0/b01/bundles/jtreg_bin-5.0.zip/jtreg/lib/javatest.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/5.0/b01/bundles/jtreg_bin-5.0.zip/jtreg/lib/jtreg.jar \\
    /opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.jdk/jdk-15/fastdebug/bin/java \\
        -Dtest.class.path.prefix=/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/serviceability/dcmd/gc/HeapDumpCompressedTest_id0.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg/serviceability/dcmd/gc:/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/test/lib \\
        -Dtest.file=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg/serviceability/dcmd/gc/HeapDumpCompressedTest.java \\
        -Dtest.src=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg/serviceability/dcmd/gc \\
        -Dtest.src.path=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg/serviceability/dcmd/gc:/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/lib \\
        -Dtest.classes=/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/serviceability/dcmd/gc/HeapDumpCompressedTest_id0.d \\
        -Dtest.class.path=/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/serviceability/dcmd/gc/HeapDumpCompressedTest_id0.d:/opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/classes/1/test/lib \\
        -Dtest.vm.opts=-XX:MaxRAMPercentage=6 \\
        -Dtest.tool.vm.opts=-J-XX:MaxRAMPercentage=6 \\
        -Dtest.compiler.opts= \\
        -Dtest.java.opts='-XX:+CreateCoredumpOnCrash -XX:+UseZGC' \\
        -Dtest.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.jdk/jdk-15/fastdebug \\
        -Dcompile.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.jdk/jdk-15/fastdebug \\
        -Dtest.timeout.factor=4.0 \\
        -Dtest.root=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/src.full/open/test/hotspot/jtreg \\
        -Dtest.modules='java.base/jdk.internal.misc java.compiler java.management jdk.internal.jvmstat/sun.jvmstat.monitor' \\
        -Dtest.nativepath=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.test/hotspot/jtreg/native \\
        --add-modules java.base,java.compiler,java.management,jdk.internal.jvmstat \\
        --add-exports java.base/jdk.internal.misc=ALL-UNNAMED \\
        --add-exports jdk.internal.jvmstat/sun.jvmstat.monitor=ALL-UNNAMED \\
        -XX:MaxRAMPercentage=6 \\
        -XX:+CreateCoredumpOnCrash \\
        -XX:+UseZGC \\
        -Djava.library.path=/opt/mach5/mesos/work_dir/jib-master/install/jdk-15+27-1351/linux-x64-debug.test/hotspot/jtreg/native \\
        -XX:+UseSerialGC \\
        com.sun.javatest.regtest.agent.MainWrapper /opt/mach5/mesos/work_dir/slaves/63712a43-4eaa-429c-95b4-483ac8241123-S648/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/11e13040-164e-4f7b-b283-44f454297add/runs/3fba3bdc-5897-478f-8f2a-bf4e33a8ced9/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_serviceability/serviceability/dcmd/gc/HeapDumpCompressedTest_id0.d/main.0.jta
result: Failed. Unexpected exit from test [exit code: 1]


test result: Failed. Unexpected exit from test [exit code: 1]


Please notice that the test @run specifies '-XX:+UseSerialGC'
and the test is also invoked with '-XX:+UseZGC' probably from
the task definition.