deadlock

Deadlock is a situation where two or more processes waiting for an event to complete, but all processes wait for indefinite time.

       we have to 

•  characterize the deadlock    
•  prevent the deadlock
• detect and avoid the deadlock
• recovery from deadlock

  For that there are algorithms to provide execution softly

synchronization

                             synchronization is mechanism refers to the orderly execution of processes so that it can ensure that only one process executing in critical section(mutual exclusion).it is implemented in kernel mode.
note: critical section:
Here critical section refers to the memory shared by two or more processes.
ex:
Consider two processes increment and decrement. These two processes perform operations on common variable counter which is stored in memory.
We can divide the counter++ process in to few atomic operations.
                                 register1=counter             //value of counter loaded to register from memory
                                 register1=register1+1        //value is incremented by one
                                 counter=register1             //again updated value is stored in memory
 same way counter-- can be divided as
                                 register2=counter
                                 register2=register2-1
                                 counter=register2
  Above three atomic in two processes must execute in order to have good result.
  Let counter=9
                If we execute increment and decrement processes sequentially, the result is same 9.
  But if we allow to access these two processes to manipulate counter  in which the atomic operations presented  previously interleaved in some arbitrary order.one such interleaving is
      T0:    increment       execute      register1=counter              {register1=9}
      T1:    increment       execute      register1=counter+1          {register1=10}
      T2:    decrement      execute      register2=counter              {register2=9}
      T3:    decrement      execute      register2=counter-1           {register1=8}
      T4:    increment       execute      counter=register1              {register1=10}
      T5:    decrement      execute      counter=register2              {register1=8}
     We come across three possible solutions after executing the sequence.
     1) Above sequence will result  8.
     2) If we reverse the order of execution of T4 and T5, the result is 10.
     3) If two processes executer sequentially, the result is 9.
      Above three possibility results in race condition.

       To avoid race condition ,we should follow some algorithms that will result in sequential execution of each process.

world population

The world's population will rise to 9.7 billion in 2050 from the current level of 7.1 billion .....

of these around 4 billions are starve for water.

let treat water as precious and not to waste as our part.

pollution ever

It was between the late 18th century and early 19th century that the Industrial Revolution boomed and flourished throughout developing countries across the globe.
Not only did it bring economic change to the scene, but environmental changes as well. More air, water, and land pollutants were introduced to nature. Natural resources started to be abused and depleted during this period, which ultimately resulted in the degradation of the environment in astronomical levels.

what a strength!!!!!

Just as earthquakes are rated on the Richter scale, tornadoes are rated on a scale from F-0 to F-5. F-0 and F-1 storms can collapse chimneys and toss mobile homes off their foundations. They have the strength to push cars off roads. F-2 and F-3 tornadoes can tear away roofs and lift and toss heavy cars. F-4 and F-5 tornadoes are so strong they can pick up and carry entire buildings a distance, toss steel beams, and crunch cars.

weather of world

effect of global warming

This has been the warmest decade since 1880. In 2010, global surface temperatures tied 2005 as the warmest on record, according to the National Oceanic and Atmospheric Administration. Scientists say that the earth could warm by an additional 7.2 degrees Fahrenheit during the 21st century if we fail to reduce emissions from burning fossil fuels, such as coal and oil. This rise in average temperature will have far-reaching effects on the earth's climate patterns and on all living things. Many of these changes have already begun.