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Java Performance Urban Legends
An anonymous reader writes "Urban legends are kind of like mind viruses; even though we know they are probably not true, we often can't resist the urge to retell them (and thus infect other gullible "hosts") because they make for such good storytelling. Most urban legends have some basis in fact, which only makes them harder to stamp out. Unfortunately, many pointers and tips about Java performance tuning are a lot like urban legends -- someone, somewhere, passes on a "tip" that has (or had) some basis in fact, but through its continued retelling, has lost what truth it once contained. This article examines some of these urban performance legends and sets the record straight."
I wonder to what extent this exists in other languages? For example, there is an oft-cited tip that says using persistent database applications with LAMP applications increases performance. I've found in actual practice that this depends on a lot of factors such as server load, amount of available memory, etc.
I remember in my Turbo Pascal programming days (heh) that a lot of people said that using Units would degrade performance. So I tried it both ways and it never really made a difference, for my applications anyways.
I'd say before taking someone's word for it on a performance enhancing technique, test it out. Because not everything you read is true, and not everything you read will apply to every environment or every application.
My journal has hot
Interesting. As a guy who's been a die-hard PostgreSQL for a number of years, and who recently accepted a job doing hardcore MySQL administration, I was dreading it, because everyone knows MySQL has bad transaction management, horrible administration nightmares, and is only good for developers.
And I'm sure MySQL DBAs all know PostgreSQL is slow, bloated, and is only good for huge database rollouts.
Except, well. You get the gist. I'm replying to this article because I now know first-hand that both camps are getting a lot of it wrong.
I've written up what began as a final in-depth studied proof that MySQL wasn't ready for the corporate environment (because I'm a PostgreSQL guy, see?) but ended up reluctantly having to conclude MySQL is slightly more ready for the corporate environment than PostgreSQL!
The writeup is on a wiki, so feel free to register and add your own experience. Please be ready to back up your opinions with facts.
fifth sigma, inc.
Exactly how does "string require careful attention"? I've seen this statement a couple of times, but only to suspect that many people don't really understand what Java Strings are.
The first mistake, of course, is that people think that (a == b) == a.equals(b) which is, of course, only true if a and b are constant strings or one have invoked intern() on them.
The second is to not realize that string concatenation with the "+" operator is a special case and only syntactic sugar for StringBuffer operations. Thus, someone not familiar with Java may accidentally generate huge amount of StringBuffer objects in loops.
However, both these things are very fundamental Java knowledge and among the first thing you learn when studying Java. It's obvious that you don't start coding serious Java without knowing how try..catch..finally works, and equally obvious that you should the know about the deals with the String class.
Really, I cant tell if the java programming language is slow, Synchronization is really slow, Declaring classes or methods final makes them faster or Immutable objects are bad for performance.
But I can tell you, the that almost every Administration application that runs java, sucks out my soul. Trying to run java applications over X at long distances makes me want to commit suicide. (Lucky theres VNC, so its almost usable...) (I think its a Shared memory problem with the way it works with X windows.)
Then there is the damn JVM's that each app needs, and how i can have multiple versions loaded, so each application works correctly. Java 1.1/1.2/1.3/1.4 and now 1.5 should take even more disk space. Doesnt seem anything is upgradable in java.
And lets not forget, about how Java likes to interact with all custom window manager replacements on windows. For some reason the screen flickers every time you run a java app. (Havnt seen any answers, but it messes with lightstep, blackbox, geoshell, and even stardock applications.)
Humm, and cut/paste sucks, yes you can use key combos, but sometimes in windows, its nice to select all, and copy. (Minor bitch, but still annoying when you have switch ways of doing things...)
If you cant have command line, and you must have a GUI, for gods sake use a HTML. I now make it a point to go with vendors without Java interfaces, they clearly dont use their own products on a day to day basis.
BTW, i said java Interfaces, not Java Beans, etc. We have java running on solaris, works fine, other than the memory leaks. Its the Admin applications that use Java that are crap.
I wonder to what extent this exists in other languages?
Probably lots. Everywhere.
As a crude approximation, 90% of the time is due to 10% of the code. Improving the "efficiency" of the 90% of the code that is responsible for only 10% of the time tends to be counter-productive. Of course there are no easy magic rules for how to improve the 10% of the code that is responsible for 90% of the time, or even identify exactly what that 10% really is.
What does work is to have a sense of how long things should take and find and cure whatever is taking much longer than it should.