Process Synchronization is a mechanism used to coordinate the execution of multiple processes/threads that access shared resources, ensuring mutual exclusion, data consistency, and correct ordering of operations.
On the basis of synchronization, processes are categorized as one of the following two types:
- Independent Process: The execution of one process does not affect the execution of other processes.
- Cooperative Process: A process that can affect or be affected by other processes executing in the system.
Process Synchronization is the coordination of multiple cooperating processes in a system to ensure controlled access to shared resources, thereby preventing race conditions and other synchronization problems.
Improper Synchronization in Inter Process Communication Environment leads to following problems:
- Inconsistency: When two or more processes access shared data at the same time without proper synchronization. This can lead to conflicting changes, where one process’s update is overwritten by another, causing the data to become unreliable and incorrect.
- Loss of Data:Â Loss of data occurs when multiple processes try to write or modify the same shared resource without coordination. If one process overwrites the data before another process finishes, important information can be lost, leading to incomplete or corrupted data.
- Deadlock:Â Improper resource allocation and synchronization can lead to deadlock, where processes wait indefinitely for resources held by one another.
Role of Synchronization in IPC
- Preventing Race Conditions: Ensures processes don’t access shared data at the same time, avoiding inconsistent results.
- Mutual Exclusion: Allows only one process in the critical section at a time.
- Process Coordination: Lets processes wait for specific conditions (e.g., producer-consumer).
- Deadlock Prevention: Proper synchronization and resource-management techniques can help prevent or avoid deadlocks.
- Safe Communication: Ensures data/messages between processes are sent, received and processed in order.
- Fairness: Some synchronization mechanisms can provide fair access to shared resources and reduce starvation.
Types of Processes Based on Synchronization
The two primary type of process Synchronization in an Operating System are:
- Competitive: Two or more processes are said to be in Competitive Synchronization if and only if they compete for the accessibility of a shared resource.
Lack of Proper Synchronization among Competing process may lead to either Inconsistency or Data loss. - Cooperative: Two or more processes are said to be in Cooperative Synchronization if and only if they get affected by each other i.e. execution of one process affects the other process.
Lack of Proper Synchronization among Cooperating process may lead to Deadlock.
Example: Let's consider a Linux command:
>>ps/grep "chrome"/wc
- ps command produces list of processes running in linux.
- grep command find/count the lines form the output of the ps command.
- wc command counts how many words are in the output.
Therefore, three processes are created which are ps, grep and wc. grep takes input from ps and wc takes input from grep.
From this example, we can understand the concept of cooperative processes, where some processes produce and others consume and thus work together. This type of problem must be handled by the operating system, as it is the manager.
Required conditions for Process Synchronization
1. Critical Section: A critical section is the part of a process where shared data or resources are accessed or modified. Mutual exclusion ensures that only one process/thread executes its critical section for a particular shared resource at a time.
2. Race Condition: A race condition occurs when multiple processes/threads concurrently access shared data, and the final result depends on the order or timing of their execution.
3. Pre-emption: The OS temporarily suspends a running process and gives the CPU to another process. If a process is preempted while accessing shared data, proper synchronization must ensure that another process cannot incorrectly access or modify the shared data.
