Re: [libvirt] [PATCH] dynamic debug patch

[Daniel Veillard <veillard redhat com>]

On Wed, Nov 05, 2008 at 08:15:31PM +0000, Daniel P. Berrange wrote:
> On Wed, Nov 05, 2008 at 08:49:23PM +0100, Daniel Veillard wrote:
> >   Okay, that's an API, expecting the app will use it. What i want is
> > allow debug without the application being modified which is rather
> > different.
> 
> I don't think libraries have any business hooking into application
> signal handlers, because each app has its own preferred debugging
> infrastructure.

  And sometimes you just can't expect the app to pass it. SIGUSR2
is hooked in gamin library, which for quite a while was linked to
all desktop apps. This never raised any problem, but allowed to get
debug informations in situations where it's hard to activate a logger.
The more complex the interaction of the library with the system the
more it's useful to have this kind of debugging available in my opinion.

> In Java, you'd want to hook all this info into log4j,

  You're still thinking in terms of application driven logging, and
this mechanism is different. They suit different purpose.

Daniel

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