All,
I am working my way through performance tuning the roller code. One
of the things we are planning on doing is ensuring that Roller
performs well without the page caches within it (we are trying to
reduce the amount of memory that it uses and instead want to leverage
a reverse proxy for caching pages). Again, you are welcome to all
this code, once we clear legal (this will probably be after xmas at
this point).
This has uncovered a number of things that I'll probably send separate
e-mails about, however one thing that has turned up is decorators. At
the moment, if a theme has a decorator (and some have for no good
reason) it causes the entire page to be written into memory twice
(once for the cache and once for the decorator, the decorator can be
subsequently garbage collected, but these are still large allocations
if we are rendering lots of entries).
I also noticed that the Template guide makes no mention of decorators,
so I was wondering if this is something that Roller still officially
supports. It it isn't supported could we remove the code for
decorators from VelocityRenderer. It's a simple change i.e. just run
the else block (see below) and it would eliminate the rather large
allocations made by the StringWriter.
Let me know what you think,
Thanks,
Rob
if(velocityDecorator != null) {
/**
* We only allow decorating once, so the process isn't
* fully recursive. This is just to keep it simple.
*/
// render base template to a temporary StringWriter
StringWriter sw = new StringWriter();
velocityTemplate.merge(ctx, sw);
// put rendered template into context
ctx.put("decorator_body", sw.toString());
log.debug("Applying decorator "+velocityDecorator.getName());
// now render decorator to our output writer
velocityDecorator.merge(ctx, out);
} else {
// no decorator, so just merge template to our output writer
velocityTemplate.merge(ctx, out);
}
