The document discusses the circuit breaker pattern for fault tolerance. The circuit breaker pattern helps prevent cascading failures and improves performance by detecting and preventing calls to failing services. It does this by monitoring for failures and opening a circuit to block calls when a service is unavailable or failing too frequently, helping avoid wasting resources on failed calls. The circuit breaker can be in closed, open, or half-open states depending on success/failure thresholds and reset timeouts. The document provides an example implementation using Akka circuit breakers in Java and Scala.

1. LE CIRCUIT BREAKER
PATTERN
Tolérance Aux Pannes
Avec
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2. Mouhcine Moulou
@mouloumouhcine
Consultant Scala
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3. 3

4. Service 1 Service 2
PROBLÈME
4

5. PROBLÈME
Service 1 Service 2
Gaspillage des ResourcesVM (Thread, Mémoire, etc.)
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6. PROBLÈME
Service 1 Service 2
timeout
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7. PROBLÈME
Service 1 Service 2
timeout
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Performance

8. PROBLÈME
Service 1
Service 3
Service 2
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9. PROBLÈME
Service 1
Service 3
Service 2
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10. PROBLÈME
Service 1
Service 3
Service 2
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11. PROBLÈME
Service 1
Service 3
Service 2
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12. CASCADING FAILURES
12

13. SOLUTION
13

14. SOLUTION
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15. « Let It Crash & Handle with Grace. »
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16. Service 1 Service 2
CIRCUIT BREAKER
16

17. Service 1 Service 2
CIRCUIT BREAKER
17

18. Service 1 Service 2
CIRCUIT BREAKER
Closed
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19. Service 1 Service 2
CIRCUIT BREAKER
Open
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20. CIRCUIT BREAKER
Closed
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21. CIRCUIT BREAKER
Closed Open
Max Failures
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22. CIRCUIT BREAKER
Closed Open
Half Open
?
ResetTimeout
Max Failures
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23. CIRCUIT BREAKER
Closed Open
Half Open
?
ResetTimeout
KO
OK
Max Failures
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24. EXEMPLE (AKKA IMPLEMENTATION)
CircuitBreaker breaker = new CircuitBreaker(
getContext().dispatcher(), // L'actor System
getContext().system().scheduler(), // Scheduler
50, // maxFailures
Duration.create(10, "s"), // Call Timeout
Duration.create(1, "m") // Reset Timeout
);
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25. EXEMPLE (AKKA IMPLEMENTATION)
// Sans Circuit Breaker
return dangerousCall();
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26. EXEMPLE (AKKA IMPLEMENTATION)
// Callable
new Callable<String>() {
public String call() throws Exception {
return dangerousCall();
}
}
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27. EXEMPLE (AKKA IMPLEMENTATION)
// Avec Circuit Breaker
// Appel Java
breaker.callWithSyncCircuitBreaker(
new Callable<String>() {
public String call() throws Exception {
return dangerousCall();
}
}
);
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28. EXEMPLE (AKKA IMPLEMENTATION)
// Avec Circuit Breaker
// Appel Scala
breaker.callWithCircuitBreaker(
Future( dangerousCall())
)
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29. CIRCUIT BREAKER
29
Avantages
•Réponse rapide.
•Meilleur utilisation des resources.
•Cascading failures.
•Monitoring.

30. CIRCUIT BREAKER
30
Avantages
•Réponse rapide.
•Meilleur utilisation des resources.
•Cascading failures.
•Monitoring.
Inconvénients
• Impossibilité de filtrer les exceptions

31. CIRCUIT BREAKER
31
ESSAYEZ LE !
Avantages
•Réponse rapide.
•Meilleur utilisation des resources.
•Cascading failures.
•Monitoring.
Inconvénients
• Impossibilité de filtrer les exceptions

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