On 17.05.2016 07:53, Alain Stalder wrote:
That looks very good to me :)
I will definitely try out the InvokerHelper.removeClass(clazz) with
added ClassInfo removal plus Introspector.flushFromCaches(clazz) and see
if I can get garbage collection before reaching the limit on Metaspace
or Heap.
And, maybe something like the following could be added to the
GroovyClassLoader? Thinking aloud:
Assuming the following is true: Any class can only be garbage collected
once its ClassLoader can be garbage collected, because each class keeps
a reference to its ClassLoader (so that it can use it to load further
classes when needed when running methods).
not only the class, the classloader internals also keep such a
reference. And I mean java.lang.ClassLoader here.
So why not have the GroovyClassLoader keep a set of all classes it
compiled itself and were loaded and offer a new ~
GroovyClassLoader#finalCleanup() method that removes meta information
for all these classes so that they would become immediately eligible for
garbage collection? (I guess InvokerHelper.removeClass(clazz) and
Introspector.flushFromCaches(clazz), but whatever is needed...)
GroovyClassLoader (GCL) actually represents a tree of class loaders. for
each compilation GCL will spawn an instance of InnerLoader. Since two
different compilations are supposed to know each others classes a list
of classes is kept in GCL itself (see classCache). The inner loader
itself is not referenced by GCL. Because of that list GCL has the
clearCache method to remove classes from previous compilations.
Why did we use this structure? GCL is supposed to offer you the
possibility to compile the same class multiple times. That means you
will get the same class multiple times. At the same time a class must be
defined under the same name only once in a given defining class loader.
As a result trying to define a class, that already exists under that
name results in an error. A classloading constraint is actually to
return the same class instance each time you request a class with a
certain name. Is implies the error before.... it also means GCL is
breaking those constraints knowingly.
Anyway... I think such a cleanup method is misplaced in GCL, since it
spans beyond the classloader... how about GroovySystem?
bye Jochen
