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

[Aleksey Shipilev]

On Mon, 7 Feb 2022 17:14:29 GMT, Alexey Pavlyutkin <duke at openjdk.java.net> wrote:

>> 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));

Or even:


LogStreamHandle(Trace, interpreter, oopmap) st;

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