| Process | Thread |
|---|---|
| A program loaded into memory with all the resources it needs | An executable unit within a process . |
| Allocated their own memory space. . | Threads of a process operate within the address space of the process |
| More expensive to create as memory needs to be allocated | Easier to create since they do not require a separate memory space |
| Context switching between processes is more expensive | Context-switching between threads is less expensive . |
| Process are heavy-weight operations | Threads are lighter weight operations . |
| Process don't share memory with other processes. They are independent of each other . | Threads share memory with other threads of the same process. Operating in the same space, threads are interdependent. Threads separate concurrency from protection |
| Inter process communication is expensive | Inter thread communication can be faster as they share memory space |
Multi-threading
In multi-threading a process has multiple threads and tries to execute multiple parts of a program (threads) at the same time. It allows for maximum utilization of the CPU
Benefits of Multi-threading
Reduced Resource usage All threads in a process share resources such as memory, data, files etc Threads require less overhead to create, maintain and manage than processes.
Maximum utilization of CPU Exploits parallelism in a multi-processor system Simultaneous and symmetric use of multi processors for computation and I/O
Responsiveness Large or complex requests don't block other requests for services
Improved throughput Many compute operations and I/O requests are executed within a single process
Program structure simplification Complex program structures can be simplified as simple routines can be written for each activity Allows for more adaptiveness to wide variation in user demands
Improved Communication Useful in coordinating programs. Multiple threads of a process sharing memory allows for or low latency communication between separate tasks within a process