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

[Ioi Lam]

On Tue, 9 Feb 2021 09:20:45 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> $ 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:
>>  - [x] Linux x86_64, affected test (default), passes
>>  - [x] Linux x86_64, affected test (`-XX:-CompactStrings`), passes
>>  - [x] Linux x86_64, affected test (`-XX:+CompactStrings`), passes
>
> Anyone? :)

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?

https://github.com/openjdk/jdk/blob/8f4c15f6417e471b372f74460fa94b9d84c4811d/test/hotspot/jtreg/runtime/CompactStrings/TestMethodNames.java#L29

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

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PR: https://git.openjdk.java.net/jdk/pull/2355