many SWT apps, using native look and feel, still feel slowish (think azureus/vuze if not eclipse). Some AWT apps are perfectly snappy e.g. jedit opens a file faster than macvim on my box.
My belief is that apart form some overhead in AWT against native toolkit, 90% of the laggish experience in java apps is due to poor coding.
In turn, this is probably a byproduct of the java platform/language (abuse threads cause they are easier than an event loop, abuse locking cause synchronized is more obvious than util.concurrent, avoid thinking of memory management cause you have a GC, do not pay attention to proper data structures cause you can get away with builtin collections etc)
First one I think of (cause I redid it today, in ruby :) is:
you need to keep a list of lines you already processed in a large log analysis.
I'd just use a Set (which is a hash underneath) and get done, although I'd have saved a bunch of overhead (memory allocations, gc pressure) using a bloom filter.
sorry I thought I replied yesterday but apparently my comment got lost.
Using a (hash)set instead of a bloom filter caused memory usage to explode, which in turn led to memory thrashing/swapping which in turn led to slow processing times.
The rest of the code runs in constant time (well, linear in the size of the item, with num(items) >> size(items[n]) ) and it did work fine for smaller inputs.
hard to estimate I'm sorry. The first naive implementation had been running for more than 15 minutes before I thought it as too much and killed it.
Rewrote version run all in about 5.
My belief is that apart form some overhead in AWT against native toolkit, 90% of the laggish experience in java apps is due to poor coding.
In turn, this is probably a byproduct of the java platform/language (abuse threads cause they are easier than an event loop, abuse locking cause synchronized is more obvious than util.concurrent, avoid thinking of memory management cause you have a GC, do not pay attention to proper data structures cause you can get away with builtin collections etc)