Garbage collection



Een vreemd fenomeen: garbage collection:
http://en.wikipedia.org/wiki/Garbage_collection_%28computer_science%29
Many computer languages require garbage collection, either as part of the language specification (e.g. Java, C#, and most scripting languages) or effectively for practical implementation (e.g. formal languages like lambda calculus); these are said to be garbage collected languages.

The original method involves a naive mark-and-sweep in which the entire memory set is touched several times.

Eigenlijke is het een vorm van memory recycling.

Java kent het:
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/System.html#gc%28%29
Runs the garbage collector.

Calling the gc method suggests that the Java Virtual Machine expend effort toward recycling unused objects in order to make the memory they currently occupy available for quick reuse. When control returns from the method call, the Java Virtual Machine has made a best effort to reclaim space from all discarded objects.

The call System.gc() is effectively equivalent to the call:

 Runtime.getRuntime().gc()

Taaltje, he!
Let op de woorden: suggests en effort
En dan die syntax: Runtime.getRuntime()
En dan die keuze stress: effectively equivalent of toch niet?

Maar PHP ook:
http://www.perplexedlabs.com/2008/02/25/php-garbage-collection-and-memory-leaks/

En JavaScript:
http://blogs.msdn.com/ericlippert/archive/2003/09/17/53038.aspx

De vraag is: waar gebeurt de garbage collection: op de (web)server of in de browser?
Zie deze IE6 ellende:
http://ajaxian.com/archives/garbage-collection-in-ie6

What can you do about this?

• a) Ask your IE 6 users to patch up
• b) Ask your IE 6 users to upgrade to IE 7
• c) Ask your IE 6 users to change browser
• d) Optimize your application by reducing code size and finding the balancing point between improved performance from keeping state local and keeping your working set to a manageable size. Always explicitly dispose objects when they are no longer needed by removing event handlers and dereferencing properties.

Geweldig deze verbetersuggesties!
Schokkend is ook deze link:
http://ispiders.blogspot.com/2007/09/ie6-is-crap-by-design.html
I give up. I have had it. Internet Explorer 6 absolutely sucks.

En hoe groot is de maximale heap?
En wie lekt geheugen en hoeveel?
Hoe complexer de code, des te meer er gelekt zal gaan worden.
En mark en sweeps worden gaande weg duurder en duurder.
Prik je er toch gewoon een gieg erbij.
Of gewoon wat vaker rebooten: http://en.wikipedia.org/wiki/Booting

Als afsluiter deze:
http://www.allbusiness.com/technology/internet-technology/707140-1.html
Before 1996, almost no political candidates were using the Internet for purposes of transmitting messages to large audiences. Some campaigns, as Myers (1993) and Davis (1999) point out, used electronic mail to communicate, but for the most part these would be "point-to-point"-type messages designed