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explain the advantage of monitor???
Rajni
on 2010-10-21 09:30:00The Java language and runtime system support thread synchronization through the use of monitors, which were first outlined in C. A. R. Hoare\'s article Monitors: An Operating System Structuring Concept (Communications of the ACM, 17(10), 549-557, 1974). A monitor is associated with a specific data item (a condition variable) and functions as a lock on that data. When a thread holds the monitor for some data item, other threads are locked out and cannot inspect or modify the data. The code segments within a program that access the same data from within separate, concurrent threads are known as critical sections. In the Java language, you mark critical sections in your program with the synchronized keyword. More at http://journals.ecs.soton.ac.uk/java/tutorial/java/threads/monitors.html
RUPAM
on 2010-11-12 10:30:00advantage and disadvntages of monitor: The reasons why the picture is retangular, relates back partly to early technological development (the Baird design scanned the picture in horizontal strips so it became \'custom\' to develop from this design), & partly due to the conventions of film cameras (which whether still or moving used rectangular frames). Having \'standardised\' this through the early development, the actual 4.3 picture ratio was fixed firstly in the US with the NTSC standard, & subsequently with PAL & SECAM (which had the advantage of knowing that the colour technology was imminent so set their standards to accomodate it whereas NTSC had to be back compatible so is inferior at showing colours esp red). Originally, televsion tubes were circular (as are radar screens) at the front & used a \'mask\' to make the picture retangular, however as technology developed, it was possible to make them both more rectangular & flatter. Likewise, as they are \'boxed\' items (the tube sits in a box), it is a more efficient to have a rectangular tube than a rounded one. Moving on to monitors, whilst the original mainstream uses for PCs were as business machines (ie for wordprocessing & accounting) where text or figures is better stored on a rectangular screen, by the time they were being introduced people were used to screens being rectangular & in 4.3, & the manufacturing processes were designed around that spec. Wide-screen, in slight contrast, was largely decided by showing focus groups a whole set of different ratio screens & asking them which they prefer. This in itself became a further proof of the \"Golden Mean\" (based on the Fibonacci sequence), since, almost without exception, people chose a 1:1.618 one. All the way through, people have been demanding flatter & more rectangular tubes, & all of the recording, editing, broadcast & playback technology has been developed to work with these systems, so it\'s not much of a surprise that plasma & LCD screens (which could be any shape) kept to the same formats.