Limiting the Number of Concurrent Connections in a Spring Boot REST API
I'm reviewing some code and I've been banging my head against this for hours. I'm having trouble with I'm relatively new to this, so bear with me. I'm working on a Spring Boot REST API that needs to handle a important amount of traffic, but I want to limit the number of concurrent connections to prevent server overload. I've tried using a `Semaphore` but I'm running into issues where it doesn't seem to limit the connections as expected. Here’s a snippet of my controller: ```java @RestController @RequestMapping("/api") public class MyController { private final Semaphore semaphore = new Semaphore(5); // limit to 5 concurrent connections @GetMapping("/data") public ResponseEntity<String> getData() { try { if (semaphore.tryAcquire(1, TimeUnit.SECONDS)) { // Simulating processing time Thread.sleep(2000); return ResponseEntity.ok("Data processed"); } else { return ResponseEntity.status(HttpStatus.SERVICE_UNAVAILABLE) .body("Too many requests, please try again later."); } } catch (InterruptedException e) { Thread.currentThread().interrupt(); return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR) .body("Internal server behavior"); } finally { semaphore.release(); } } } ``` I expect that the API should return a `503 Service Unavailable` status when there are more than 5 concurrent requests, but instead, I’m still seeing multiple requests being processed simultaneously. I'm using Spring Boot 2.5.6 and the default embedded Tomcat server. I've also checked the server logs and there are no exceptions being thrown. Am I missing something in the configuration, or is there a better way to handle limiting concurrent requests in Spring Boot? Any insights would be greatly appreciated! For context: I'm using Java on Linux. What am I doing wrong? How would you solve this? For context: I'm using Java on Ubuntu 20.04. What's the best practice here? The stack includes Java and several other technologies.