Questions
1 of 10
1Explain the fan-out and fan-in concurrency pattern with a practical example.
2How does the select statement work with multiple channels, including a default case?
3How does Go's GMP scheduler work and how does it affect concurrency design?
4Describe how you would approach a Go service that needs to process Kafka events with exactly-once semantics.
5What is a goroutine leak and how do you detect and prevent one?
6When should you use sync.Mutex vs channels for shared state?
7How would you implement a distributed task queue in Go without using an external framework?
8What is a goroutine, and how does it differ from an OS thread?
9What is the difference between a buffered and unbuffered channel?
10Design a worker pool for processing 100,000 jobs with back-pressure and graceful shutdown.
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01 / 10

Explain the fan-out and fan-in concurrency pattern with a practical example.

Fan-out distributes work across multiple goroutines reading from a shared input channel. Fan-in merges results from multiple output channels into a single channel for the consumer.

Fan-out and fan-in pipeline
Key design considerations
  1. 1

    Always close channels when producers are done — ranging goroutines exit cleanly

  2. 2

    Use context cancellation to stop all workers when one fails or timeout occurs

  3. 3

    Buffer the merged channel to avoid one slow worker blocking others

  4. 4

    WaitGroup in fan-in ensures merged channel is closed only after all workers finish

  5. 5

    For CPU-bound work, limit fan-out to runtime.NumCPU() workers