Cluster module for scaling Quiz

Explore key concepts of the cluster module for scaling processes in server environments. This quiz assesses your understanding of worker management, inter-process communication, and effective scaling strategies relevant to high-availability systems.

1. Master vs Worker Responsibilities

   In a clustered server environment, what is the primary role of the master process when using the cluster module?

   1. Handling all incoming client requests directly
   2. Managing and spawning worker processes
   3. Performing CPU-intensive computations exclusively
   4. Maintaining persistent database connections

   Explanation: The master process in a cluster environment is mainly responsible for managing and spawning worker processes, which enhances scalability and failure resilience. It does not directly handle incoming client requests, as that is typically delegated to workers. It is not dedicated solely to CPU-intensive computations, nor does it focus on maintaining persistent database connections. Both of those tasks can be managed by workers, depending on the application’s design.

2. Scenario: Scaling a Web Server

   If your single-threaded web server struggles with heavy traffic, how does the cluster module help improve its performance?

   1. By doubling the server’s RAM automatically
   2. By installing security patches automatically
   3. By reducing the latency of each HTTP request
   4. By spawning multiple processes to utilize all CPU cores

   Explanation: The cluster module allows a web server to utilize all available CPU cores by spawning multiple worker processes, each handling a subset of incoming requests. It does not increase the server’s physical RAM or directly reduce latency per HTTP request. Additionally, the cluster module does not manage security patches, which should be handled independently.

3. Inter-Process Communication

   Which method does the cluster module use for communication between the master and worker processes?

   1. Through an IPC (Inter-Process Communication) channel
   2. Environment variable updates
   3. Sending emails between processes
   4. Direct shared memory access

   Explanation: The cluster module utilizes IPC (Inter-Process Communication) channels for sending messages between the master and worker processes, ensuring coordinated operation. Direct shared memory access is not typically used due to process isolation. Environment variable updates do not provide real-time, secure communication. Sending emails is unrelated to process management and would introduce unnecessary delay.

4. Worker Termination Handling

   What should the master process do if a worker exits unexpectedly in a cluster setup?

   1. Send all traffic to the failed worker
   2. Restart the entire server
   3. Ignore the exit and reduce total workers
   4. Respawn a new worker process

   Explanation: When a worker exits unexpectedly, the master process should respawn a new worker to maintain optimal performance and availability. Ignoring the exit would decrease resource utilization, while restarting the entire server is usually unnecessary and disruptive. Sending traffic to a failed worker would result in lost requests and increased downtime.

5. Sticky Sessions in a Clustered Environment

   Why might sticky sessions be necessary when using the cluster module with stateful applications such as chat servers?

   1. To maximize memory usage per worker
   2. To ensure a user's requests are always handled by the same worker
   3. To assign random workers to each incoming request
   4. To prevent all users from accessing the same worker

   Explanation: Sticky sessions route a user’s requests to the same worker, which is important for stateful applications where session data is kept in memory. Assigning random workers could result in session data loss or inconsistency, while preventing shared access or trying to maximize memory use are not relevant reasons. The main intent is session consistency, not load balancing by randomness or memory usage.