Introduction to Threading Interview Questions and Answers
THREAD is known as a lightweight process. A thread can also be understood in a way that it is a path that executes within a process. The concept behind Multi-threading is to achieve parallelism which helps in being multi-process oriented. A very fine line definition that separates threading and multi-threading is in the way of handling the associated process. The below-mentioned scenario will help us to think in a similar way.
Imagine while working on any given browser you need to collect the data related to Indian IT industry, in the process of collecting the details you tried to open a new tab window (in the same browser) but unfortunately can’t. This is one way to explain what threading is exactly and how multi-threading can be a blessing for the user. So, in a browser, multiple tabs can be different threads. One another example will clear the thinking more precisely, the MS Word application uses multiple threads while working, one thread for formatting purpose whereas another for processing the inputs and so on.
Now, if you are looking for a job which is related to Threading then you need to prepare for the 2019 Threading Interview Questions. It is true that every interview is different as per the different job profiles. Here, we have prepared the important Threading Interview Questions and Answers which will help you get success in your interview.
In this 2019 Threading Interview Questions article, we shall present 10 most important and frequently used Threading interview questions. These questions are divided into two parts are as follows:
Part 1 – Threading Interview Questions (Basic)
This first part covers basic Threading Interview Questions and Answers
Q1. What is the difference between multi-thread programming and single thread programming?
Answer:
In a Multi-threading process, multiple threads work at the same time. There is no event loop while pooling in a multi-threading model. The CPU time is utilized in a better way with no time wastage. The Idle time is least. A more efficient program is the outcome of a multi-threading process. A special behavior of multi-threading programming is that when one thread is paused the other run as usual.
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A single thread runs at one time in a Single thread programming, this model uses a process event loop during pooling. The CPU time is not capitalized in a proper way as it has more idle time. The effectiveness of single thread programming is less because when one thread is paused the system waits until the thread is resumed, which result in less effective programs.
Q2. What is a process and how it is different from a thread?
Answer:
This is the basic Threading Interview Question asked in an interview. The primary difference between the two lies in their working behavior. The threads of a related process run in shared memory location whereas in a process the memory spaces are different. This behavior of thread makes it more efficient in term of responsiveness with its counterpart. Since threads are associated with one another, they share code, data and OS details with one another. One more thing about the thread is that they have their own Program counter (PC), register sets and stack space.
Q3. Elaborate on the life cycle of a thread?
Answer:
Whenever a thread is created it is in the “New Born” state. After this, the thread can in 2 states namely
- Running
- Runnable
The thread will call the start method to navigate or move to run or runnable state from newborn state. Runnable means that your thread is ready to execute but it is waiting for the availability of the processor. The moment a processor is allocated the state gets changed to running from runnable. But, to change the state from running to runnable there are dedicated methods to do so (like in JAVA there is YIELD method). Now to block a thread form either of the two states (i.e. running or runnable) there are 3 methods namely
- Suspend
- Sleep
- Wait
Also to run an already blocked thread there are different methods like
- Resume
- Notify
Lastly, STOP method is needed to make the state of the thread to change from newborn, running, runnable or blocked to DEAD state.
Note – There can be multiple one-word interview question based on this – like name the method to change the state from running to block or anyone mentioned above.
Q4. What is a ThreadLocal class?
Answer:
ThreadLocal class in Java enables you to create variables. These variables can be read and write by the same methods. So, if two threads are executing the same code but the codes have a ThreadLocal variable, the chances are that the two threads cannot see each other ThreadLocal variables.
Let us move to the next Threading Interview Questions.
Q5. What is a daemon thread in Java?
Answer:
User threads are the front performer and demon threads are like assistants. The assistant helps in completing a task. Once the task gets completed, there is no need for the performer and in return assistant also quits the place. These are mostly created by JVM. These threads (demons) are mainly created to perform the background task like garbage collection etc.
Part 2 – Threading Interview Questions (Advanced)
Let us now have a look at the advanced Threading Interview Questions.
Q6. How to create threads in Java?
Answer:
By extending Thread Class a thread can be created.
Public class MyThreadClass extends Thread {
Public void run () {
System.out.println (“Thread name is :”+Thread.currentThread().getName());
Try{
Thread.sleep(1000);
} catch (InterruptedException) {
e.printStackTrace();
}
}
}
Q7. Provide the names of all the sections or details that a thread contains in a TCB(Thread control block)?
Answer:
Thread Identifier
- Stack Pointer
- Program Counter
- Thread State
- Thread register set
- Parent process pointer
Let us move to the next Threading Interview Questions.
Q8. What is Thread Join() in threading?
Answer:
The class of a thread contains several methods, join() and sleep()are 2 among them. The thread.join() method is used to call a thread and blocks it until a thread is terminated.
Q9. How to debug a thread in C#?
Answer:
This is the most asked Threading Interview Questions in an interview. In visual studio, there is a shortcut available for better productivity with limiting the time.
- CTRL+T+T or snowflakes = This limits the execution to the current thread only and freezes all other threads.
- CTRL+T+J or Next button = allows switching to next single thread. This brings changes only to the current thread and freezes all the other thread.
Q10. What does the Address of the operator do in the background?
Answer:
The AddressOf operator creates the object in the background process method. A type-safe, object-oriented function pointer is the structure of any delegates in VB.NET. Once the thread has been initiated, one can execute the code by calling the Start() method for the thread.
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