[slf4j-user] SLF4JBridgeHandler performance warning

[Joern Huxhorn]

Hi Ben,

yes, you understood it correctly.

The main problem is that you have to decide about the lowest level  
that you'll ever receive from the BridgeHandler.

Everything above that level will generate a logging event in  
j.u.logging. Only after that event has been generated (including fully  
generating its message), the actually used SLF4J implementation will  
have a chance to drop it.

This is very unfortunate and is the main reason why I consider  
j.u.logging the worst logging API out there.

Regards,
Joern.


On 12.04.2010, at 17:10, Ben Pickering wrote:

> Hi
>
> In our application we use several libraries that log using  
> j.u.logging, and we want to send them to the slf4j-wrapped logback  
> setup we use everywhere else.  For this we're using the  
> SLF4JBridgeHandler class.
>
> On the Javadoc page for SLF4JBridgeHandler http://www.slf4j.org/api/org/slf4j/bridge/SLF4JBridgeHandler.html 
>  there's a warning that the class comes with a performance cost, and  
> I'm keen to understand the nature of this.
>
> My assumption is that the issue relates to the case where the  
> j.u.logging level is finer than the logback level.  Processing done  
> by j.u.logging is wasted because a logging call never results in a  
> message being written; it never 'makes it through' logback because  
> of its higher level.  If the library is generating lots of FINEST  
> calls, this could be a hit.
>
> However, if the j.u.logging level is set high, e.g. to INFO, then  
> j.u.logging itself never makes the effort, and so there'll be no  
> additional performance impact.
>
> Is this a correct assessment?  Or is there more that I should be  
> aware of?
>
>
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