RFR: 8267926: AsyncLogGtest.java fails on assert with: decorator was not part of the decorator set specified at creation. [v6]

[Xin Liu]

On Thu, 3 Jun 2021 05:48:55 GMT, Xin Liu <xliu at openjdk.org> wrote:

>> The root cause of the intermittent failure is that _decorators in LogDecorations 
>> may be inconsistent with LogOutput::_decorators. It could happen when gtest disables a
>> Log output via set_log_config(TestLogFileName, "all=off").
>> 
>> Since we copy the entire logDecorations, it's reasonable to copy _decorator as well. 
>> LogDecorator is a bitmask of uint. It's even smaller than a reference on LP64 platforms.
>> 
>> This patch not only fixes intermittent crash in JDK-8267926, but also fixes JDK-8267952.
>> Two hazards of async logging in `LogConfiguration::configure_output` are eliminated. 
>> This patch also adds a storestore barrier to make sure it's safe on weak consistency machines.
>
> Xin Liu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Safeguard _stream is NULL due to rotation.

src/hotspot/share/logging/logConfiguration.cpp line 282:

> 280:   if (!enabled) {
> 281:     for (LogTagSet* ts = LogTagSet::first(); ts != NULL; ts = ts->next()) {
> 282:       assert(!ts->has_output(output), "The node of output should been removed in ts->set_output_level.");

should be removed by ts->set_output_level()

test/hotspot/gtest/logging/test_logConfiguration.cpp line 305:

> 303:     }
> 304: 
> 305:     // Take turn logging with different decorators, either None or All.

This comment is wrong.  I turn on/off the tagset logging here.

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PR: https://git.openjdk.java.net/jdk/pull/4257