Juniour .NET developer - Some interview questions

Thread vs process

• A process is an executing instance of an application
• A thread is a path of execution within a process. Also, a process can contain multiple threads.

It’s important to note that a thread can do anything a process can do. But since a process can consist of multiple threads, a thread could be considered a ‘lightweight’ process. Thus, the essential difference between a thread and a process is the work that each one is used to accomplish. Threads are used for small tasks, whereas processes are used for more ‘heavyweight’ tasks – basically the execution of applications.
Another difference between a thread and a process is that threads within the same process share the same address space, whereas different processes do not. This allows threads to read from and write to the same data structures and variables, and also facilitates communication between threads. Communication between processes – also known as IPC, or inter-process communication – is quite difficult and resource-intensive.

Summary

1. Threads are easier to create than processes since they don't require a separate address space. 
2. Multithreading requires careful programming since threads share data strucures that should only be modified by one thread at a time. Unlike threads, processes don't share the same address space. 
3. Threads are considered lightweight because they use far less resources than processes. 
4. Processes are independent of each other. Threads, since they share the same address space are interdependent, so caution must be taken so that different threads don't step on each other. This is really another way of stating #2 above. 
5. A process can consist of multiple threads.

Programming patterns

• Builder - Unlike the abstract factory pattern and the factory method pattern whose intention is to enable polymorphism, the intention of the builder pattern is to find a solution to the telescoping constructor anti-pattern. The telescoping constructor anti-pattern occurs when the increase of object constructor parameter combination leads to an exponential list of constructors. Instead of using numerous constructors, the builder pattern uses another object, a builder, that receives each initialization parameter step by step and then returns the resulting constructed object at once.
• The factory method pattern is a creational pattern which uses factory methods to deal with the problem of creating objects without specifying the exact class of object that will be created.