FYI xbean has runtime constraints bcel skips (valid read and loaded info are consistent) Le 14 juin 2013 18:56, "sebb" <seb...@gmail.com> a écrit :
> On 14 June 2013 17:35, Christopher Schultz <ch...@christopherschultz.net> > wrote: > > Mark, > > > > On 6/14/13 12:21 PM, Mark Thomas wrote: > >> On 14/06/2013 16:57, Christopher Schultz wrote: > >>> Mark, > >>> > >>> On 6/14/13 3:16 AM, Mark Thomas wrote: > >>>> On 14/06/2013 03:31, Christopher Schultz wrote: > >>>> > >>>>> It might be nice if this were not a one-of-many decision, but if a > >>>>> client could choose more than one type. A bit-mask or a list of > >>>>> scan-types would be nice. I could see the same type of scanner being > >>>>> used for multiple different purposes. > >>>> > >>>> That is what ServletContainerIniiializers are for. > >>> > >>> Well, crap. I had never seen those before. > >>> > >>> I'm curious, though. Thinking about this the other day with a colleague > >>> who was complaining about some kind of Spring configuration that > >>> evidently loaded every class available on the classpath and kept them > in > >>> memory (thus leading to heap and PermGen issues), I concluded that the > >>> only sane way to do this kind of probing would be to probe everything > in > >>> a ClassLoader that was intended to be discarded after the probing as to > >>> avoid loading classes unnecessarily. > >>> > >>> If an SCI retains a reference to any of the Class objects in the > >>> Set<Class> parameter, that hypothetical throw-away ClassLoader is no > >>> longer thrown-away. > >> > >> The early Tomcat 7 implementations did it like this - loaded every class > >> and then examined the class object. More recent implementations use BCEL > >> to look at the byte code. It is faster and uses less memory. We also use > >> caching to ensure each class is only processed once. > > That functionality sounds like it might be useful as a general purpose > library item, possibly as part of a utility jar for Commons BCEL. > For example JMeter has to scan classes for certain interfaces on > startup. It's current implementation is a bit wasteful. > > > Cool. What Classloader gets used to actually load the Class objects, > > though? > > BCEL reads class files as files. > > http://commons.apache.org/proper/commons-bcel/ > > > In the pathological case of @HandlesType('java.lang.Object') > > that means everything gets loaded into .. the WebappClassLoader? > > > > One could imagine a case where an SCI wants to look at everything, but > > then only ends up caring about 2% of what's been loaded. Is that just > > the price you have to pay for inspecting everything -- that you > > seriously waste PermGen? (at least for current Oracle JVMs) > > > > -chris > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@tomcat.apache.org > For additional commands, e-mail: dev-h...@tomcat.apache.org > >
