The following test failed in the JDK21 CI:

runtime/handshake/HandshakeTimeoutTest.java

Here's a snippet from the log file:

#section:driver
----------messages:(10/314)----------
command: driver HandshakeTimeoutTest
reason: User specified action: run driver HandshakeTimeoutTest
started: Thu Jun 08 00:07:12 UTC 2023
Mode: agentvm
Agent id: 20
Timeout refired 480 times
Timeout information:
--- Timeout information end.
finished: Thu Jun 08 00:25:47 UTC 2023
elapsed time (seconds): 1114.304
----------configuration:(16/2322)----------

<snip>

----------System.out:(9/3199)----------
Command line: [/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+26-2315/linux-aarch64-debug.jdk/jdk-21/fastdebug/bin/java -cp /opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S1202/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/cd44baf6-092f-4661-a29c-adac949180d2/runs/a8c08a39-9b81-4625-911c-585bed94f792/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_runtime/classes/0/runtime/handshake/HandshakeTimeoutTest.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+26-2315/src.full/open/test/hotspot/jtreg/runtime/handshake:/opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S1202/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/cd44baf6-092f-4661-a29c-adac949180d2/runs/a8c08a39-9b81-4625-911c-585bed94f792/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_runtime/classes/0/testlibrary:/opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S1202/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/cd44baf6-092f-4661-a29c-adac949180d2/runs/a8c08a39-9b81-4625-911c-585bed94f792/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_runtime/classes/0/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.2/1/bundles/jtreg-7.2+1.zip/jtreg/lib/jtreg.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.2/1/bundles/jtreg-7.2+1.zip/jtreg/lib/junit-platform-console-standalone-1.9.2.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.2/1/bundles/jtreg-7.2+1.zip/jtreg/lib/testng-7.3.0.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.2/1/bundles/jtreg-7.2+1.zip/jtreg/lib/jcommander-1.78.jar:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.2/1/bundles/jtreg-7.2+1.zip/jtreg/lib/guice-4.2.3.jar -XX:MaxRAMPercentage=6.25 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/20/36/bundles/linux-aarch64/jdk-20_linux-aarch64_bin.tar.gz/jdk-20 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S1202/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/cd44baf6-092f-4661-a29c-adac949180d2/runs/a8c08a39-9b81-4625-911c-585bed94f792/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_runtime/tmp -XX:+UnlockExperimentalVMOptions -XX:LockingMode=2 -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+HandshakeALot -XX:GuaranteedSafepointInterval=10 -XX:ParallelGCThreads=1 -XX:ConcGCThreads=1 -XX:CICompilerCount=2 -XX:+UnlockExperimentalVMOptions -XX:HandshakeTimeout=50 -XX:-CreateCoredumpOnCrash HandshakeTimeoutTest$Test ]
[2023-06-08T00:07:12.855566071Z] Gathering output for process 425423
[2023-06-08T00:24:39.032496596Z] Waiting for completion for process 425423
[2023-06-08T00:24:39.033703163Z] Waiting for completion finished for process 425423
Output and diagnostic info for process 425423 was saved into 'pid-425423-output.log'
[2023-06-08T00:24:39.044912100Z] Waiting for completion for process 425423
[2023-06-08T00:24:39.045004620Z] Waiting for completion finished for process 425423
[2023-06-08T00:24:39.045066061Z] Waiting for completion for process 425423
[2023-06-08T00:24:39.046061546Z] Waiting for completion finished for process 425423
----------System.err:(18/775)----------
 stdout: [[0.347s][error][handshake] Handshake timeout: HandshakeALot(0x0000ffff882b07f8), pending threads: 1
[0.348s][error][handshake] JavaThread 0x0000ffffa432b360 has not cleared handshake op: 0x0000ffff882b07f8
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGILL (0x4) at pc=0x0000ffffab082b48 (sent by kill), pid=425423, tid=425482
#
# JRE version: Java(TM) SE Runtime Environment (21.0+26) (fastdebug build 21-ea+26-LTS-2315)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-ea+26-LTS-2315, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
# Problematic frame:
# C [libc.so.6+0x23b48][thread 425475 also had an error]
];
 stderr: []
 exitValue = 134


JavaTest Message: Test complete.

result: Error. Agent error: java.lang.Exception: Agent 20 timed out with a timeout of 480 seconds; check console log for any additional details

While there is a SIGILL crash, the artifacts link does not include
an hs_err_pid file.