Hi Tom,
Thanks for your observation and your code proposal; always welcome.
I have some concerns that the caching of non-existing classes could be
exploited and bloat the cache. Maybe we’d need to use WeakHashMap
(and/or soft references) instead?
> I'm not sure why BaseX tries to load our xqm as Java Modules, but what I
> noticed is that Reflect.forName caches the positive case (i.e., the class is
> found), but not the negative case (i.e., the class is not found).
Sounds like an interesting finding; maybe there’s something we can
optimize here. Could you possibly provide us a little self-contained
example that demonstrates the behavior?
Thanks in advance,
Christian
On Wed, Oct 17, 2018 at 9:53 AM Tom Rauchenwald (UNIFITS)
<tom.rauchenw...@unifits.com> wrote:
>
> Hi BaseX-Team,
>
>
> when profiling some of our tests i found that we spend some time in
> Reflect.forName().
>
> We have 2 xquery modules in the repo (we don't call java code directly).
>
>
> I'm not sure why BaseX tries to load our xqm as Java Modules, but what I
> noticed is that Reflect.forName caches the positive case (i.e., the class is
> found), but not the negative case (i.e., the class is not found).
>
> I've changed the code to cache the negative case as well (see below), and
> noticed an improvement of about 5 percent.
>
> Our tests create and query loads of small databases, so this is maybe quite
> an artificial speedup.
>
>
> I could provide a PR if this is a worthwhile improvement in your opinion (and
> if I'm not missing something obvious).
>
>
> We're still on BaseX 8.7.6 in case that matters, as far as I could see the
> Code didn't change in BaseX 9.
>
>
> Thanks,
>
> Tom
>
>
> Code:
>
>
> public static Class<?> forName(final String name) throws
> ClassNotFoundException {
> Class<?> c = CLASSES.get(name);
>
> if(c == null) {
> if (CLASSES.containsKey(name)) {
> throw new ClassNotFoundException(name);
> } else {
> try {
> c = Class.forName(name);
> } catch (ClassNotFoundException e) {
> CLASSES.put(name, null);
> throw e;
> }
> if (!Modifier.isPublic(c.getModifiers())) throw new
> ClassNotFoundException(name);
> CLASSES.put(name, c);
> }
> }
> return c;
> }
>
