8260934: java/lang/StringBuilder/HugeCapacity.java fails without Compact Strings

[shipilev]

$ CONF=linux-x86_64-server-fastdebug make run-test TEST=java/lang/StringBuilder/HugeCapacity.java TEST_VM_OPTS=-XX:-CompactStrings

STDERR:
java.lang.OutOfMemoryError: Required length exceeds implementation limit
at java.base/java.lang.AbstractStringBuilder.newCapacity(AbstractStringBuilder.java:259)
at java.base/java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:229)
at java.base/java.lang.AbstractStringBuilder.ensureCapacity(AbstractStringBuilder.java:213)
at java.base/java.lang.StringBuilder.ensureCapacity(StringBuilder.java:87)
at HugeCapacity.testLatin1(HugeCapacity.java:49)
at HugeCapacity.main(HugeCapacity.java:37)

I went back and forth in fixing this test, and I think the best we can do is sense the current setting on CompactStrings and choose the test configuration based on that. The alternative is to use WhiteBox within the test (tried, it is quite a bit ugly). Note that this test deliberately does not run -XX:-CompactStrings even when vm.opt.final.CompactStrings returns true (= "available"), because that might mean TEST_VM_OPTS=-XX:+CompactStrings is in effect, and we have the VM option conflict.

Additional testing:

• Linux x86_64, affected test (default), passes
• Linux x86_64, affected test (-XX:-CompactStrings), passes
• Linux x86_64, affected test (-XX:+CompactStrings), passes

---

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Issue

• JDK-8260934: java/lang/StringBuilder/HugeCapacity.java fails without Compact Strings

Reviewers

• Ioi Lam (@iklam - Reviewer)

Download

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$ git checkout pull/2355

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[mlbridge]

Webrevs

• 01: Full - Incremental (856676d)
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[shipilev]

Anyone? :)

[iklam]

Having two @test blocks makes the maintenance more difficult. I had to do a diff to find out the difference between the two blocks.

There's an existing test that explicitly tests both -XX:+CompactStrings and -XX:-CompactStrings. Maybe we can do the same thing?

jdk/test/hotspot/jtreg/runtime/CompactStrings/TestMethodNames.java

Line 29 in 8f4c15f

* @run main/othervm -XX:+CompactStrings TestMethodNames

* @run main/othervm -Xms5G -Xmx5G -XX:+CompactStrings HugeCapacity true
* @run main/othervm -Xms5G -Xmx5G -XX:-CompactStrings HugeCapacity false

[shipilev]

Having two @test blocks makes the maintenance more difficult. I had to do a diff to find out the difference between the two blocks.

There's an existing test that explicitly tests both -XX:+CompactStrings and -XX:-CompactStrings. Maybe we can do the same thing?

No, I don't think we can. In other tests, the conflict between -XX:+CompactStrings and -XX:-CompactStrings would select one of the modes, so both test configurations would degenerate into one config (run twice). In this test, however, the compact strings mode defines whether the affected subtest would pass or fail, because it pokes at the allocation limit. So, we have to sense the actual setting of CompactStrings here.

As I said, the alternative would be sensing it programmatically via WhiteBox, at expense at single @test config, but with WhiteBox ceremony.

[iklam]

There's an existing test that explicitly tests both -XX:+CompactStrings and -XX:-CompactStrings. Maybe we can do the same thing?

No, I don't think we can. In other tests, the conflict between -XX:+CompactStrings and -XX:-CompactStrings would select one of the modes, so both test configurations would degenerate into one config (run twice).

I tried running jtreg -vmoptions:-XX:+CompactStrings TestMethodNames.java and the log file shows:

(the first @test)
-XX:+CompactStrings \
-XX:+CompactStrings \
com.sun.javatest.regtest.agent.MainWrapper /jdk2/tmp/jtreg/work/runtime/CompactStrings/TestMethodNames.d/main.0.jta

(the second @test)
-XX:+CompactStrings \
-XX:-CompactStrings \
com.sun.javatest.regtest.agent.MainWrapper /jdk2/tmp/jtreg/work/runtime/CompactStrings/TestMethodNames.d/main.1.jta

The VM options specified by the @test line are appended after the options specified by -vmoptions. So this test is executed in two different configurations (not twice in the same configuration).

[shipilev]

The VM options specified by the @test line are appended after the options specified by -vmoptions. So this test is executed in two different configurations (not twice in the same configuration).

Right, okay, so the last option wins, this is good. We can do what the updated version does. ...but then we also need to handle platforms where -XX:-CompactStrings is set by platform config (e.g. on ARM). -XX:+CompactStrings would be ignored there, and we cannot run test with true then. I think only ARM32 is affected, so it would be filtered by existing @requires, so it can be resolved later.

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8260934: java/lang/StringBuilder/HugeCapacity.java fails without Compact Strings

Reviewed-by: iklam

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At the time when this comment was updated there had been 15 new commits pushed to the master branch:

• 05c6009: 8259656: fixpath.sh changes broke _NT_SYMBOL_PATH in RunTests.gmk
• ef7ee3f: 8225081: Remove Telia Company CA certificate expiring in April 2021
• 7c565f8: 8261209: isStandalone property: remove dependency on pretty-print
• 01d9280: 8261299: Use-after-free on failure path in LinuxPackage.c, getJvmLauncherLibPath
• a00b130: 8261356: Clean up enum G1Mark
• becee64: 8261279: sun/util/resources/cldr/TimeZoneNamesTest.java timed out
• f395ee0: 8261306: ServiceLoader documentation has malformed Unicode escape
• 8f4c15f: 8198540: Dynalink leaks memory when generating type converters
• edd5fc8: 8261096: Convert jlink tool to use Stream.toList()
• 2f893c2: 8260337: Optimize ImageReader lookup, used by Class.getResource
• ... and 5 more: https://git.openjdk.java.net/jdk/compare/5183d8ae1eec86202eace2c4770f81edbc73cb68...master

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[shipilev]

/integrate

[openjdk]

@shipilev Since your change was applied there have been 19 commits pushed to the master branch:

• 752f92b: 6211242: AreaAveragingScaleFilter(int, int): IAE is not specified
• 3af334a: 6211257: BasicStroke.createStrokedShape(Shape): NPE is not specified
• 4619f37: 8261472: BasicConstraintsExtension::toString shows "PathLen:2147483647" if there is no pathLenConstraint
• 699a3cd: 8223188: Removed unnecessary #ifdef __cplusplus from .cpp sources
• 05c6009: 8259656: fixpath.sh changes broke _NT_SYMBOL_PATH in RunTests.gmk
• ef7ee3f: 8225081: Remove Telia Company CA certificate expiring in April 2021
• 7c565f8: 8261209: isStandalone property: remove dependency on pretty-print
• 01d9280: 8261299: Use-after-free on failure path in LinuxPackage.c, getJvmLauncherLibPath
• a00b130: 8261356: Clean up enum G1Mark
• becee64: 8261279: sun/util/resources/cldr/TimeZoneNamesTest.java timed out
• ... and 9 more: https://git.openjdk.java.net/jdk/compare/5183d8ae1eec86202eace2c4770f81edbc73cb68...master

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