Sunday 12 June 2011

Java 8 wishlist

I have blogged before about my dissatisfaction with the rate of improvement of the Java platform. While the situation is understandable, it still leaves me annoyed. Below is an updated wish list that I would like to see in Java 8.

I am increasingly considering getting my hands dirty in adding some of these features. If only I had more time. So my first wish is for a clock with a big 'stop the world' button on it. Having an infinite amount of time, with high energy levels, no risk of rsi and no risk of interruptions would be great. Please create this for me Mr S. Hawking.


jvm
    support jar level constant pools to reduce class sizes
    enhanced gc
    transactional memory support
    add method parameter names to reflection
    access to javaadoc from api (provide in optional packaging that can be accessed via reflection); include comment following abstract method.

Simple syntax sugar
    .?
    multi line strings
    versioned jar file/module system
    drop the annoying diamond operator (<>) added in Java 7 but keep the functionality
    optional method parameters with default values
    language syntax for reflection
    language support for collections
    pre condition support on method signatures

More involved language features
    mix ins
    closures
    Language support for custom types
    replace try-close with keyword; keyword declares that an object is not to escape the stack
    Inferred type support (eg var s = "abc"; s is strongly typed to String why double declare it)

Friday 3 June 2011

Slow networks

Interesting points from http://highscalability.com/blog/2011/6/1/why-is-your-network-so-slow-your-switch-should-tell-you.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+HighScalability+%28High+Scalability%29


Network operators get calls from application guys saying the network is slow, but the problem is usually dropped packets due to congestion. It's not usually latency, it's usually packet loss. Packet loss causes TCP to back off and retransmit, which causes applications to appear slow.

Packet loss can be caused by a flakey transceiver, but the problem is usually network congestion. Somewhere on the network there's fan-in, a bottleneck develops, queues build up to a certain point, and when a queue overflows it drops packets. Often the first sign of this happening is application slowness.