The following test failed in the JDK26 CI:

gc/stringdedup/TestStringDeduplicationInterned.java#Parallel

Here's a snippet from the log file:

----------System.err:(161/11512)----------
Exception in thread "main" java.lang.RuntimeException: Deduplication has not occurred, load history: could not gather load statistics from system
at gc.stringdedup.TestStringDeduplicationTools.waitForDeduplication(TestStringDeduplicationTools.java:220)
at gc.stringdedup.TestStringDeduplicationTools$InternedTest.main(TestStringDeduplicationTools.java:418)

 stdout: [[0.019s][info][gc] Using Parallel
[0.129s][info][stringdedup,init] String Deduplication is enabled
[0.209s][debug][stringdedup ] Starting string deduplication thread
[0.209s][debug][stringdedup,phases,start] Idle start
Begin: InternedTest
Creating strings: total=10, unique=10
Begin: Full GC 1/3
[0.467s][info ][gc ] GC(0) Pause Full (System.gc()) 4M->1M(94M) 26.814ms
[0.495s][debug][stringdedup,phases ] Idle end: 286.059ms
[0.495s][debug][stringdedup,phases,start] Active start
[0.495s][debug][stringdedup,phases,start] Process start
End: Full GC 1/3
Creating strings: total=10, unique=10
Begin: Full GC 2/3
[0.524s][info ][gc ] GC(1) Pause Full (System.gc()) 2M->1M(94M) 27.954ms
End: Full GC 2/3
Creating strings: total=10, unique=10
[0.547s][debug][stringdedup,phases ] Process end: 51.810ms
[0.547s][debug][stringdedup,phases ] Active end: 51.859ms
[0.547s][info ][stringdedup ] Concurrent String Deduplication 178/10160.0B (new), 82/2576.0B (deduped), avg 25.4%, 51.810ms of 51.859ms
[0.547s][debug][stringdedup ] Last Process: 1/51.810ms, Idle: 1/286.059ms
[0.547s][debug][stringdedup ] Inspected: 323
[0.547s][debug][stringdedup ] Known: 86( 26.6%)
[0.547s][debug][stringdedup ] Shared: 59( 18.3%)
[0.547s][debug][stringdedup ] New: 178( 55.1%) 10160.0B
[0.547s][debug][stringdedup ] Replaced: 1( 0.6%)
[0.547s][debug][stringdedup ] Deleted: 0( 0.0%)
[0.547s][debug][stringdedup ] Deduplicated: 82( 25.4%) 2576.0B( 25.4%)
[0.547s][debug][stringdedup ] Skipped: 2 (dead), 0 (incomplete), 0 (shared)
[0.547s][debug][stringdedup ] Total Process: 1/51.810ms, Idle: 1/286.059ms
[0.547s][debug][stringdedup ] Inspected: 323
Begin: Full GC 3/3
[0.547s][debug][stringdedup ] Known: 86( 26.6%)
[0.547s][debug][stringdedup ] Shared: 59( 18.3%)
[0.547s][debug][stringdedup ] New: 178( 55.1%) 10160.0B
[0.547s][debug][stringdedup ] Replaced: 1( 0.6%)
[0.547s][debug][stringdedup ] Deleted: 0( 0.0%)
[0.547s][debug][stringdedup ] Deduplicated: 82( 25.4%) 2576.0B( 25.4%)
[0.547s][debug][stringdedup ] Skipped: 2 (dead), 0 (incomplete), 0 (shared)
[0.547s][debug][stringdedup ] Table: 178 values in 503 buckets, 1 dead (0)
[0.547s][debug][stringdedup,phases,start] Idle start
[0.574s][info ][gc ] GC(2) Pause Full (System.gc()) 2M->1M(94M) 26.377ms
[0.599s][debug][stringdedup,phases ] Idle end: 51.218ms
[0.599s][debug][stringdedup,phases,start] Active start
[0.599s][debug][stringdedup,phases,start] Process start
[0.599s][debug][stringdedup,phases ] Process end: 0.082ms
End: Full GC 3/3
[0.601s][debug][stringdedup,phases ] Active end: 1.867ms
[0.601s][info ][stringdedup ] Concurrent String Deduplication 1/32.0B (new), 21/1296.0B (deduped), avg 38.0%, 0.082ms of 1.867ms
[0.601s][debug][stringdedup ] Last Process: 1/0.082ms, Idle: 1/51.218ms
[0.601s][debug][stringdedup ] Inspected: 23
[0.601s][debug][stringdedup ] Known: 21( 91.3%)
[0.601s][debug][stringdedup ] Shared: 1( 4.3%)
[0.601s][debug][stringdedup ] New: 1( 4.3%) 32.0B
[0.601s][debug][stringdedup ] Replaced: 0( 0.0%)
[0.601s][debug][stringdedup ] Deleted: 0( 0.0%)
[0.601s][debug][stringdedup ] Deduplicated: 21( 91.3%) 1296.0B(4050.0%)
[0.601s][debug][stringdedup ] Skipped: 0 (dead), 0 (incomplete), 0 (shared)
[0.601s][debug][stringdedup ] Total Process: 2/51.891ms, Idle: 2/337.276ms
[0.601s][debug][stringdedup ] Inspected: 346
[0.601s][debug][stringdedup ] Known: 107( 30.9%)
[0.601s][debug][stringdedup ] Shared: 60( 17.3%)
[0.601s][debug][stringdedup ] New: 179( 51.7%) 10192.0B
[0.601s][debug][stringdedup ] Replaced: 1( 0.6%)
[0.601s][debug][stringdedup ] Deleted: 0( 0.0%)
[0.601s][debug][stringdedup ] Deduplicated: 103( 29.8%) 3872.0B( 38.0%)
[0.601s][debug][stringdedup ] Skipped: 2 (dead), 0 (incomplete), 0 (shared)
[0.601s][debug][stringdedup ] Table: 179 values in 503 buckets, 1 dead (0)
[0.601s][debug][stringdedup,phases,start] Idle start
Creating strings: total=10, unique=10
Begin: Young GC 1/1
[0.966s][info ][gc ] GC(3) Pause Young (Allocation Failure) 39M->1M(94M) 8.514ms
End: Young GC 1/1
Creating strings: total=10, unique=10
Begin: Full GC 1/3
[1.254s][info ][gc ] GC(4) Pause Full (System.gc()) 2M->1M(94M) 40.191ms
End: Full GC 1/3
Creating strings: total=10, unique=10
Begin: Full GC 2/3
[1.322s][info ][gc ] GC(5) Pause Full (System.gc()) 2M->1M(94M) 26.706ms
[1.352s][debug][stringdedup,phases ] Idle end: 751.339ms
[1.352s][debug][stringdedup,phases,start] Active start
[1.352s][debug][stringdedup,phases,start] Process start
End: Full GC 2/3
Creating strings: total=10, unique=10
Begin: Full GC 3/3
[1.381s][info ][gc ] GC(6) Pause Full (System.gc()) 2M->1M(94M) 27.613ms
End: Full GC 3/3
Waiting for deduplication...
[1.409s][debug][stringdedup,phases ] Process end: 56.223ms
[1.409s][debug][stringdedup,phases ] Active end: 56.311ms
[1.409s][info ][stringdedup ] Concurrent String Deduplication 356/15528.0B (new), 51/1872.0B (deduped), avg 22.3%, 56.223ms of 56.311ms
[1.409s][debug][stringdedup ] Last Process: 1/56.223ms, Idle: 1/751.339ms
[1.409s][debug][stringdedup ] Inspected: 654
[1.409s][debug][stringdedup ] Known: 273( 41.7%)
[1.409s][debug][stringdedup ] Shared: 25( 3.8%)
[1.409s][debug][stringdedup ] New: 356( 54.4%) 15528.0B
[1.409s][debug][stringdedup ] Replaced: 1( 0.3%)
[1.409s][debug][stringdedup ] Deleted: 0( 0.0%)
[1.409s][debug][stringdedup ] Deduplicated: 51( 7.8%) 1872.0B( 12.1%)
[1.409s][debug][stringdedup ] Skipped: 8 (dead), 0 (incomplete), 0 (shared)
[1.409s][debug][stringdedup ] Total Process: 3/108.115ms, Idle: 3/1088.615ms
[1.409s][debug][stringdedup ] Inspected: 1000
[1.409s][debug][stringdedup ] Known: 380( 38.0%)
[1.409s][debug][stringdedup ] Shared: 85( 8.5%)
[1.409s][debug][stringdedup ] New: 535( 53.5%) 25720.0B
[1.409s][debug][stringdedup ] Replaced: 2( 0.4%)
[1.409s][debug][stringdedup ] Deleted: 0( 0.0%)
[1.409s][debug][stringdedup ] Deduplicated: 154( 15.4%) 5744.0B( 22.3%)
[1.409s][debug][stringdedup ] Skipped: 10 (dead), 0 (incomplete), 0 (shared)
[1.409s][debug][stringdedup ] Table: 535 values in 503 buckets, 11 dead (0)
[1.409s][debug][stringdedup,phases,start] Idle start
[1.409s][debug][stringdedup,phases ] Idle end: 0.021ms
[1.409s][debug][stringdedup,phases,start] Active start
[1.409s][debug][stringdedup,phases,start] Process start
[1.409s][debug][stringdedup,phases ] Process end: 0.055ms
[1.409s][debug][stringdedup,phases ] Active end: 0.096ms
[1.409s][info ][stringdedup ] Concurrent String Deduplication 1/40.0B (new), 20/1280.0B (deduped), avg 27.3%, 0.055ms of 0.096ms
[1.409s][debug][stringdedup ] Last Process: 1/0.055ms, Idle: 1/0.021ms
[1.409s][debug][stringdedup ] Inspected: 21
[1.409s][debug][stringdedup ] Known: 20( 95.2%)
[1.409s][debug][stringdedup ] Shared: 0( 0.0%)
[1.409s][debug][stringdedup ] New: 1( 4.8%) 40.0B
[1.409s][debug][stringdedup ] Replaced: 0( 0.0%)
[1.409s][debug][stringdedup ] Deleted: 0( 0.0%)
[1.409s][debug][stringdedup ] Deduplicated: 20( 95.2%) 1280.0B(3200.0%)
[1.409s][debug][stringdedup ] Skipped: 0 (dead), 0 (incomplete), 0 (shared)
[1.409s][debug][stringdedup ] Total Process: 4/108.170ms, Idle: 4/1088.636ms
[1.409s][debug][stringdedup ] Inspected: 1021
[1.410s][debug][stringdedup ] Known: 400( 39.2%)
[1.410s][debug][stringdedup ] Shared: 85( 8.3%)
[1.410s][debug][stringdedup ] New: 536( 52.5%) 25760.0B
[1.410s][debug][stringdedup ] Replaced: 2( 0.4%)
[1.410s][debug][stringdedup ] Deleted: 0( 0.0%)
[1.410s][debug][stringdedup ] Deduplicated: 174( 17.0%) 7024.0B( 27.3%)
[1.410s][debug][stringdedup ] Skipped: 10 (dead), 0 (incomplete), 0 (shared)
[1.410s][debug][stringdedup ] Table: 536 values in 503 buckets, 11 dead (0)
[1.410s][debug][stringdedup,phases,start] Idle start
];
 stderr: [Exception in thread "main" java.lang.RuntimeException: Deduplication has not occurred, load history: could not gather load statistics from system
at gc.stringdedup.TestStringDeduplicationTools.waitForDeduplication(TestStringDeduplicationTools.java:220)
at gc.stringdedup.TestStringDeduplicationTools$InternedTest.main(TestStringDeduplicationTools.java:418)
]
 exitValue = 1

java.lang.RuntimeException: Expected to get exit value of [0], exit value is: [1]
at jdk.test.lib.process.OutputAnalyzer.shouldHaveExitValue(OutputAnalyzer.java:522)
at gc.stringdedup.TestStringDeduplicationTools.testInterned(TestStringDeduplicationTools.java:551)
at gc.stringdedup.TestStringDeduplicationInterned.main(TestStringDeduplicationInterned.java:94)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:335)
at java.base/java.lang.Thread.run(Thread.java:1474)

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

result: Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: Expected to get exit value of [0], exit value is: [1]


This failure mode actually matches a much older bug that was
closed as "Other" back on 2024-03-26:

JDK-8275684 gc/stringdedup/TestStringDeduplicationInterned.java#Parallel failed: no deduplication

The relevant comment is https://bugs.openjdk.org/browse/JDK-8275684?focusedId=14660479&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14660479:

Leo Korinth added a comment - 2024-03-26 07:00
Gathering of load statistics was added in JDK-8283223 and added to test failure printouts. If this test fails again (it has not failed for a while) we can opt to use the new system load mechanism to ignore the test when the system is overloaded.

For the sighting covered by this issue, it appears that the
load info gathering mechanism didn't work since part of
the failure output is:

    load history: could not gather load statistics from system