When the event for which a thread is blocked occurs?
Options:
A. thread moves to the ready queue B. thread remains blocked C. thread completes D. a new thread is provided |
The Correct Answer Is:
- A. thread moves to the ready queue
The correct answer is A. thread moves to the ready queue.
In a multithreaded environment, when a thread is blocked, it means that it is temporarily paused or waiting for some condition to be satisfied before it can proceed with its execution. When the event for which a thread is blocked occurs, the typical behavior is for the thread to move to the ready queue. Let’s explore this in detail and explain why the other options are not correct:
A. Thread Moves to the Ready Queue (Correct Answer):
When a thread is blocked, it is not actively executing its code; instead, it is waiting for some condition to be met, such as the availability of a resource or the completion of an I/O operation. When the event or condition that caused the thread to block is satisfied or resolved, the thread becomes eligible to run again.
It is moved from the blocked state to the ready state and placed in the ready queue. Threads in the ready queue are waiting for their turn to execute, and the scheduler of the operating system or threading library determines the order in which they will run based on scheduling policies and priorities.
Now, let’s discuss why the other options are not correct:
B. Thread Remains Blocked:
This option is not correct because when the event for which a thread is blocked occurs, the thread does not remain in a blocked state indefinitely. The whole purpose of blocking a thread is to allow it to resume execution when the necessary condition or event is satisfied.
If the thread were to remain blocked even after the event occurs, it would defeat the purpose of blocking and waiting for that event.
C. Thread Completes:
This option is not accurate because the completion of a thread’s execution is a different event altogether. When a thread completes its execution, it transitions from the running state to the terminated state.
This is a final state, indicating that the thread has finished its task and will not be scheduled for execution again. It is not related to the scenario where a thread is blocked and then unblocked when a specific event occurs.
D. A New Thread Is Provided:
This option is not correct because the event for which a thread is blocked is typically related to the existing thread’s activity and not the creation of a new thread. Blocking and unblocking threads are mechanisms used to manage the execution of existing threads efficiently, particularly in scenarios where multiple threads are contending for resources or waiting for specific conditions.
Creating a new thread is a separate action taken by a program or application and is not directly related to unblocking a previously blocked thread.
In summary, option A, “thread moves to the ready queue,” is the correct answer because it accurately reflects the typical behavior in a multithreaded environment when a thread is blocked and the event for which it was blocked occurs.
The thread transitions from the blocked state to the ready state, allowing it to continue execution when it is scheduled by the thread scheduler. The other options (B, C, and D) do not accurately describe the behavior of a blocked thread in response to the occurrence of the blocking event.
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