Slow Redis Example

Demonstrates non-blocking I/O by intentionally delaying each request by 1 second.

The Point

With blocking I/O, a single-threaded server handling 5 requests that each take 1 second would need 5 seconds total (sequential processing).

With non-blocking I/O, those same 5 concurrent requests complete in ~1 second because they all sleep concurrently while the event loop handles them.

Running

# Start Redis
docker run -d -p 6379:6379 redis

# Start the server
REDIS_HOST=localhost pagi-server --app examples/slow-redis/app.pl --port 5001

Testing

Single request (~1 second)

curl http://localhost:5001/

5 concurrent requests (should be ~1 second, not 5!)

time (for i in 1 2 3 4 5; do curl -s http://localhost:5001/ & done; wait)

10 concurrent requests

time (for i in $(seq 1 10); do curl -s http://localhost:5001/ & done; wait)

Compare with fast endpoint (no delay)

curl http://localhost:5001/fast

Expected Output

Slow Redis Response
===================
Worker PID:     12345
Redis Time:     1704307200.123456
Request took:   1.002s (including 1s sleep)

This request intentionally waits 1 second to demonstrate non-blocking I/O.
Run multiple concurrent requests - they should all complete in ~1 second total!

How It Works

1. Request arrives
2. Future::IO->sleep(1) yields control to the event loop
3. Event loop can accept and process other requests during the sleep
4. After 1 second, all sleeping requests wake up
5. Each request gets Redis TIME and responds

The key is that Future::IO->sleep() is non-blocking - it doesn't block the thread, it just schedules a callback for later while the event loop continues processing other work.