Critical Section in Operating System
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The document discusses race conditions that occur when multiple processes access shared data concurrently. A critical section is a block of code that only one process can execute at a time to avoid race conditions. The critical section problem aims to ensure only one process is in its critical section at once using mutual exclusion. Mutual exclusion methods like semaphores are used to prevent simultaneous access to shared resources like global variables.
Critical Section in Operating System
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- 2. When two or more processes are reading or writing some shared data and the final result depends on who runs precisely when, is called race condition. Race condition occurs when two or more operations occur in an undefined manner. Race condition should be avoided because they can cause fine errors in applications and are difficult to debug. 2
- 3. A critical section is a block of code that only one process at a time can execute. The critical section problem is to ensure that only one process at a time is allowed to be operating in its critical section. Each process takes permission from operating system to enter into the critical section: a) Entry Section b) Remainder Section c) Exit Section 3
- 4. Solution of critical section must satisfy : a) Mutual Exclusion : If a process is executing in its critical section, then no other process is allowed to execute in the critical section. b) Progress : If no process is in the critical section, then no other process from outside can block it from entering the critical section. c) Bounded Waiting : A bound must exist on the number of times that other processes are allowed to enter their critical sections after a process has made a request to enter its critical section and before that request is granted. OS handles critical section problem by using Kernel, which is classified as : a) Preemptive Kernel b) Non-preemptive Kernel 4
- 5. Mutual exclusion methods are used in concurrent programming to avoid the simultaneous use of a common resource, such as a global variable, by pieces of computer code called critical section. Mutual exclusion can be carried out by: a) Software Method (Highly error prone) b) Hardware Method (Faster but incomplete) c) Programming Language Method 5
- 6. 1) At any time, only one process is allowed to enter in its critical section. 2) Solution is implemented purely in software. 3) A process remains inside the critical section for a bounded time only. 4) A process can not prevent other process from entering into critical section. 5) A process must not be indefinitely postponed from entering its critical section. 6
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Editor's Notes
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