Skip to main content

Monitor In Process Synchronization

    ⇰   MONITOR :-

The monitor is one of the way of achieving synchronization. The monitor is supported by programming languages to achieve mutual exclusion between processes.  Although semaphores provide a convenient and effective mechanism for process synchronization, but using semaphore incorrectly can cause timing errors that are difficult to detect.

A monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to work or block for a certain condition to become true. Monitors also have a machenism for singling other threads that their condition has been met. Monitors provide a machenism for threads to temporarily give up exclusive access in order to wait for some condition to be met.

Another definition of monitor is a thread-safe class, object or module that wraps around a mutex in order to safely allow access to a method or variable by more than ane thread. The defining charactorstics of a monitor is that its methods are executed with mutual exclusion. At each point of time, at most one thread may be executing any of its methods. By using one or more condition variable it can also provide the ability for threads to wait on a certain condition.

Monitor have the advantage of making parallel programming easier and less error prone than using other technique such as semaphore. Monitor is basically abstract data type and may contain shared data variables and procedures. It allow a single process to access the shared data variables at a time.
The representation of a monitor type cannot be used directly by the various processes. Thus, a function defined within a monitor can access only those variables declared locally within the monitor and its formal parameters. The monitor construct ensures that only one process at a time is active within the monitor. 

    ⇰   IMPORTANT POINTS :-

   i> Monitor is the collection of condition variables and procedures which are combined in  a special kind of module or a package.

 ii> The processes that are running outside the monitor can never access the internal variable of the monitor.

 iii> Only one process at a time can execute code inside monitors.

    ⇰   SYNTAX OF MONITOR :-

 monitor < monitor name >
{
  variables ;
   procedure P1 (.....)
    {
        ............
    }

   procedure P2 (.....)
    {
        ............
    }

   procedure P3 (.....)
    {
        ............
    } 

  Initialization code (.....)
   {
       ...........
   }
}

click here for post on semaphore.
Share, Follow and please comment if you find anything incorrect or to share more information about the topic discussed above.


Labels:

Comments

Post a Comment

Please comment.

Popular posts from this blog

Process Scheduling And Types of Process Schedular :-

        ⇰ PROCESS SCHEDULING Process Scheduling  is a task  of Operating System that schedules processes of different states like new, ready, waiting, terminated  and running.This scheduling helps in allocation of CPU time for each process, and Operating System allocates the CPU time for each procss. And the process scheduling plays important role to keep the CPU busy all the time.  ⏩   Followings are some objectives of Process Scheduling :-  i > To increase the amount of users within acceptable response times.  ii > To maintain the balance between response and utilization of system. iii > To decrease the enforce priorities and  give reference to the processes holding the key resources.      ⇰  PROCESS SCHEDULAR A scheduler carries out the pro cess scheduling work. Schedulers are often implemented so they keep all computer resources busy and  allows multiple users to share system resources  to achieve  multiprogramming .  There are  mainy three types of pro
8 comments
Read more

Tokens and its types in 'C'

   Tokens are the smallest individual unit of a program or in simple words it is a main part of C program.Tokens are the building blocks of any program. The smallest individual and basic unit of a C programming is called c tokens.      *    Normally there are six types of tokens in C:- i> Keywords:-          Keywords are special words that are used to give a special meaning to the program and can't be used as variable and constant.They are basically a sequence of characters that have fixed to mean. For example:-                 auto     double      long     break                 float    short        char     if                while    continue   int       void etc. All keywords must be written in lower case.It is 32 in number. ii> Identifiers:-         The identifiers are basically a token. It can be a variable's name or a label's name. So identifiers are actually a user defined data. But there are certain rules to frame an identifier. They are as follo
3 comments
Read more

Process & Its state And process control block :-

                ⇰  PROCESS :- A process can be thought of as a program in execution. Means when any program is executed it becomes process. A processwill need certain resources such as CPU time , memory, files and I/O devices to complete its task. These resources are allocated to the process either when it is created or at the time of execution.             A process is the unit of work in most systems. A system consistes of a collection of processes. All these processes may execute concurrently. Traditionally a process contained only a single thread. Most modern operating ststems now supports processes that have multiple threads.         The operating system is responsible for several important works of process management as - the creation and deletion of process, the schrduling of process, communication and deadlock handling of process. Process is broudly divided into two types:-  i> System  Process. ii> User Process. Early computers allowed only one program be ex
Post a Comment
Read more