RFR: 8354522: Clones of DecimalFormat cause interferences when used concurrently [v2]

[Johannes Graham]

On Tue, 15 Apr 2025 16:49:57 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> Johannes Graham has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - fix test summary
>>  - add test
>
> test/jdk/java/text/Format/DecimalFormat/CloneTest.java line 27:
> 
>> 25:  * @test
>> 26:  * @bug 8354522
>> 27:  * @summary Check for cloning interference
> 
> It will probably be good to mention somewhere that this test/fix addresses the issue of the same _data_ array reference being shared amongst DigitList clones.

I added more detail to the comment with the test method.

> test/jdk/java/text/Format/DecimalFormat/CloneTest.java line 48:
> 
>> 46:         AtomicInteger mismatchCount = new AtomicInteger(0);
>> 47:         DecimalFormat df = new DecimalFormat("#");
>> 48:         String _ = df.format(Math.PI); // initial use of formatter
> 
> We should probably comment the importance of this line, as without it the test will pass without the fix. (It sets the _data_ array to a non null value).

Done

> test/jdk/java/text/Format/DecimalFormat/CloneTest.java line 54:
> 
>> 52:                 DecimalFormat threadDf = (DecimalFormat) df.clone();
>> 53:                 Runnable task = () -> {
>> 54:                     for (int j = 0; j < 1000000; j++) {
> 
> We should probably make this test less costly by decreasing some values, I don't the bug requires that many iterations to be exposed. (Without the fix and the `break` statement in the test, `mismatchCount` gets up into the tens of thousands on my machine.)

For the original reproducer I wanted to be _really_ sure that it failed. I've reduced it to be more reasonable. With the current config it still gets 10-100 mismatches for me. I've limited the number of lines that get logged as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24598#discussion_r2045232675
PR Review Comment: https://git.openjdk.org/jdk/pull/24598#discussion_r2045232933
PR Review Comment: https://git.openjdk.org/jdk/pull/24598#discussion_r2045235681