[jira] [Commented] (LOGCXX-546) Multi threaded applications run at single threaded speed

["Dr Stephen L S Webb (Jira)" <lo...@logging.apache.org>]

    [ https://issues.apache.org/jira/browse/LOGCXX-546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17465083#comment-17465083 ] 

Dr Stephen L S Webb commented on LOGCXX-546:
--------------------------------------------

The benchmark https://github.com/apache/logging-log4cxx/pull/87 shows the rate of log4cxx calls to a disabled logger is greatly reduced when multiple threads are active.

In version 11.0 the call rate to a disabled logger when multiple threads are active is similar to when only a singl thread is active.

> Multi threaded applications run at single threaded speed
> --------------------------------------------------------
>
>                 Key: LOGCXX-546
>                 URL: https://issues.apache.org/jira/browse/LOGCXX-546
>             Project: Log4cxx
>          Issue Type: Bug
>    Affects Versions: 0.12.0
>            Reporter: Dr Stephen L S Webb
>            Priority: Major
>
> Accessing repository using rep = repository.lock() in Logger::isDisabled() causes all threads to be serialized when they test if their logger is enabled.
> I suggest Hierarchy hold std::weak_ptr for the Loggers instead of std::shared_ptr in LoggerMap. 
> Logger can hold a raw pointer to the LoggerRepository. The LoggerRepository destructor should then do
> {code:java}
> for (auto& item : this->loggers)
> {
>   if (auto pLogger = item.second.lock())
>     pLogger->resetRepository();
> }{code}
> Logger can then test for a NULL repositiory instead of lock() on the weak pointer



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