RFR: 8281195: Mistakenly used logging causes significant overhead in interpreter

[Alexey Pavlyutkin]

On Mon, 7 Feb 2022 16:10:57 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Fixes
>> 
>> `bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top)`
>> 
>> eliminating frequent generation of log messages with no respect of logging configuration
>> 
>> Verification: N/A (the issue does not have an observable effect)
>> 
>> Regression: hotspot_compiler (20.04 on amd64 )
>
> src/hotspot/share/interpreter/oopMapCache.cpp line 282:
> 
>> 280:   bool const is_log_enabled = log_type::is_enabled();
>> 281:   static const log_type log;
>> 282:   LogStream st(log);
> 
> Isn't this just:
> 
> 
>   const bool log = log_is_enabled(Trace, interpreter, oopmap);
>   LogStream st(Log(interpreter, oopmap)::trace());

Yes, you're right, there are many ways to say the same. Log(...)::trace() returns exactly the object represented by `log` variable. It also may be


const bool log = log_is_enabled(LogLevel::Trace, interpreter, oopmap);
LogStream st(LogTarget(LogLevel::Trace, interpreter, oopmap));

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PR: https://git.openjdk.java.net/jdk/pull/7367