Re: Java performance
boroph...@gmail.com wrote:
I am just interested in the latest stats on Java performance. A lot
of the literature appears to be out of date in this respect. Is it
true that Java performance is close to that of native compiled code?
Hunter Gratzner wrote:
Yes.
Or faster, sometimes.
Finally, I have read that garbage collection is generally more
efficient than manual memory management. Is this true, and if so,
why?
It has advantages and disadvantages. You can study the details for
ages. But in short it usually doesn't hurt and is in general "better",
unless you mess up things.
Whereas platforms without GC require more code to handle allocation and
deallocation, and will cause trouble if you mess up things.
Allocation of a new object on the heap in Java is on the order of 10x fewer
machine instructions than in C++. Deallocation of young objects, on the order
of 95% of all objects in most programs (particularly if you're versed in Java
idioms), is essentially zero cost.
More importantly, GC greatly reduces the window of opportunity for
memory-management bugs. As Hunter says, there are ways to defeat its advantages.
Furthermore, there are multiple algorithms available. Try to duplicate the
scalability of Sun's parallel GC algorithms in a non-GCed environment. The
era of the single-processor computer is giving way to a multi-processor world.
Never mind how Java's GC harmonizes with Hotspot compilation.
-
Lew