8292877: java/util/concurrent/atomic/Serial.java uses {Double,Long}Accumulator incorrectly

[shipilev]

JDK-8026344 added tests that subtly contradict the contract for {Double,Long}Accumulator-s, which breaks the tests on some platforms even in the single-threaded case.

They use accumulators with binary plus as update function and using non-zero values as identity, which breaks once accumulators create many cells, reset their values to identity, and then apply the function over them, producing unexpected values.

See the investigation on RISC-V here:
https://mail.openjdk.org/pipermail/riscv-port-dev/2022-August/000594.html

We can do what DoubleAccumulator javadocs do as the sample, namely: "For example, to maintain a running maximum value, you could supply Double::max along with Double.NEGATIVE_INFINITY as the identity."

Additional testing:

• Linux x86_64, java/util/concurrent tests

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Issue

• JDK-8292877: java/util/concurrent/atomic/Serial.java uses {Double,Long}Accumulator incorrectly

Reviewers

• Paul Sandoz (@PaulSandoz - Reviewer)
• Martin Buchholz (@Martin-Buchholz - Reviewer)
• Alan Bateman (@AlanBateman - Reviewer)

Reviewing

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[mlbridge]

Webrevs

• 00: Full (bc24297b)

[PaulSandoz]

An interesting failure!

[openjdk]

@shipilev This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8292877: java/util/concurrent/atomic/Serial.java uses {Double,Long}Accumulator incorrectly

Reviewed-by: psandoz, martin, alanb

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At the time when this comment was updated there had been 7 new commits pushed to the master branch:

• 7b81a9c: 8289764: gc/lock tests failed with "OutOfMemoryError: Java heap space: failed reallocation of scalar replaced objects"
• 76ee549: 8292329: Enable CDS shared heap for zero builds
• 14623c6: 8292739: Invalid legacy entries may be returned by Provider.getServices() call
• 568be58: 8290469: Add new positioning options to PassFailJFrame test framework
• 69448f9: 8292679: Simplify thread creation in gtest and port 2 tests to new way
• 3c2289d: 8215916: The failure reason of an optional JAAS LoginModule is not logged
• 71ab5c9: 8292816: GPL Classpath exception missing from assemblyprefix.h

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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[Martin-Buchholz]

IIRC I worked on
test/jdk/java/util/concurrent/tck/LongAdderTest.java:testSerialization
test/jdk/java/util/concurrent/tck/DoubleAdderTest.java:testSerialization
I should have added similar tests back then, to
DoubleAccumulatorTest.java
LongAccumulatorTest.java
and that would allow deletion of Serial.java as a redundant test.
I would have done that now as well, but there's nothing wrong with this fix.

[AlanBateman]

Surprising that this has lurked for 9 years without being noticed.

[shipilev]

Thank you all!

/integrate

[openjdk]

Going to push as commit 251bff6.
Since your change was applied there have been 13 commits pushed to the master branch:

• f57d342: 8292867: RISC-V: Simplify weak CAS return value handling
• 88af204: 8292494: Ensure SystemDictionary::set_platform_loader and set_system_loader are called only once
• 8d3d439: 8292903: enhance round_up_power_of_2 assertion output
• 054c23f: 8290025: Remove the Sweeper
• dc7e256: 8290376: G1: Refactor G1MMUTracker::when_sec
• 5a20bc4: 8292715: Cleanup Problemlist
• 7b81a9c: 8289764: gc/lock tests failed with "OutOfMemoryError: Java heap space: failed reallocation of scalar replaced objects"
• 76ee549: 8292329: Enable CDS shared heap for zero builds
• 14623c6: 8292739: Invalid legacy entries may be returned by Provider.getServices() call
• 568be58: 8290469: Add new positioning options to PassFailJFrame test framework
• ... and 3 more: https://git.openjdk.org/jdk/compare/c0623972cffdbcd7f80e84a1ec344fd382a4a5cc...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 251bff6.

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