The following tests timeout in the Valhalla CI on windows-x64 when the -XX:+UseCompactObjectHeaders option is used:

com/sun/jdi/valhalla/FieldWatchpointsTest.java
com/sun/jdi/valhalla/ValueArrayReferenceTest.java
com/sun/jdi/valhalla/ValueClassTypeTest.java

Here's a snippet from the FieldWatchpointsTest.java log file:

#section:main
----------messages:(12/875)----------
command: main FieldWatchpointsTest -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
reason: User specified action: run main/othervm FieldWatchpointsTest -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
started: Tue Jan 13 00:15:25.448 UTC 2026
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jdi
Process id: 12496
Timeout information:
[00:23:25.459] starting timeout handler action(s)
[00:40:41.981] timeout handler action(s) completed
--- Timeout information end.
finished: Tue Jan 13 00:40:41.983 UTC 2026
elapsed time (seconds): 1516.535
----------configuration:(3/38)----------
Boot Layer
  add modules: jdk.jdi

----------System.out:(3/426)*----------
vmOpts: '-Xmx768m -XX:MaxRAMPercentage=4.16667 -Dtest.boot.jdk=c:\\ade\\mesos\\work_dir\\jib-master\\install\\jdk\\25\\37\\bundles\\windows-x64\\jdk-25_windows-x64_bin.zip\\jdk-25 -Djava.io.tmpdir=c:\\sb\\prod\\1768263144\\testoutput\\test-support\\jtreg_open_test_jdk_jdk_svc\\tmp -XX:+CreateCoredumpOnCrash -ea -esa'
javaOpts: '-XX:+UseZGC -XX:+UseCompactObjectHeaders'
[00:23:25.458] Timeout signalled after 480 seconds
----------System.err:(1/237)----------
[2ms] run args: [-XX:+UseArrayFlattening, -XX:+UseFieldFlattening, -XX:+UseAtomicValueFlattening, -XX:+UseNullableValueFlattening, -XX:+UnlockDiagnosticVMOptions, -XX:+PrintInlineLayout, -XX:+PrintFlatArrayLayout, FieldWatchpointsTarg]
----------rerun:(50/6897)*----------


Here's a snippet from the ValueArrayReferenceTest.java log file:

#section:main
----------messages:(12/1096)----------
command: main ValueArrayReferenceTest --add-modules java.base --add-exports java.base/jdk.internal.value=ALL-UNNAMED -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
reason: User specified action: run main/othervm ValueArrayReferenceTest --add-modules java.base --add-exports java.base/jdk.internal.value=ALL-UNNAMED -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
started: Tue Jan 13 00:15:26.415 UTC 2026
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules java.base --add-exports java.base/jdk.internal.value=ALL-UNNAMED
Process id: 83352
Timeout information:
[00:23:26.432] starting timeout handler action(s)
[00:40:38.098] timeout handler action(s) completed
--- Timeout information end.
finished: Tue Jan 13 00:40:38.103 UTC 2026
elapsed time (seconds): 1511.688
----------configuration:(4/117)----------
Boot Layer
  add modules: java.base
  add exports: java.base/jdk.internal.value ALL-UNNAMED

----------System.out:(3/426)*----------
vmOpts: '-Xmx768m -XX:MaxRAMPercentage=4.16667 -Dtest.boot.jdk=c:\\ade\\mesos\\work_dir\\jib-master\\install\\jdk\\25\\37\\bundles\\windows-x64\\jdk-25_windows-x64_bin.zip\\jdk-25 -Djava.io.tmpdir=c:\\sb\\prod\\1768263144\\testoutput\\test-support\\jtreg_open_test_jdk_jdk_svc\\tmp -XX:+CreateCoredumpOnCrash -ea -esa'
javaOpts: '-XX:+UseZGC -XX:+UseCompactObjectHeaders'
[00:23:26.431] Timeout signalled after 480 seconds
----------System.err:(1/323)----------
[2ms] run args: [--add-modules, java.base, --add-exports, java.base/jdk.internal.value=ALL-UNNAMED, -XX:+UseArrayFlattening, -XX:+UseFieldFlattening, -XX:+UseAtomicValueFlattening, -XX:+UseNullableValueFlattening, -XX:+UnlockDiagnosticVMOptions, -XX:+PrintInlineLayout, -XX:+PrintFlatArrayLayout, ValueArrayReferenceTarg]
----------rerun:(51/7099)*----------


Here's a snippet from the ValueClassTypeTest.java log file:

#section:main
----------messages:(12/871)----------
command: main ValueClassTypeTest -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
reason: User specified action: run main/othervm ValueClassTypeTest -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+UseAtomicValueFlattening -XX:+UseNullableValueFlattening -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlineLayout -XX:+PrintFlatArrayLayout
started: Tue Jan 13 00:15:26.773 UTC 2026
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jdi
Process id: 77200
Timeout information:
[00:23:26.785] starting timeout handler action(s)
[00:40:42.604] timeout handler action(s) completed
--- Timeout information end.
finished: Tue Jan 13 00:40:42.606 UTC 2026
elapsed time (seconds): 1515.833
----------configuration:(3/38)----------
Boot Layer
  add modules: jdk.jdi

----------System.out:(3/426)*----------
vmOpts: '-Xmx768m -XX:MaxRAMPercentage=4.16667 -Dtest.boot.jdk=c:\\ade\\mesos\\work_dir\\jib-master\\install\\jdk\\25\\37\\bundles\\windows-x64\\jdk-25_windows-x64_bin.zip\\jdk-25 -Djava.io.tmpdir=c:\\sb\\prod\\1768263144\\testoutput\\test-support\\jtreg_open_test_jdk_jdk_svc\\tmp -XX:+CreateCoredumpOnCrash -ea -esa'
javaOpts: '-XX:+UseZGC -XX:+UseCompactObjectHeaders'
[00:23:26.785] Timeout signalled after 480 seconds
----------System.err:(1/235)----------
[2ms] run args: [-XX:+UseArrayFlattening, -XX:+UseFieldFlattening, -XX:+UseAtomicValueFlattening, -XX:+UseNullableValueFlattening, -XX:+UnlockDiagnosticVMOptions, -XX:+PrintInlineLayout, -XX:+PrintFlatArrayLayout, ValueClassTypeTarg]
----------rerun:(50/6875)*----------