CAS Performance Optimization and Troubleshooting Flashcards

What is the purpose of a circuit breaker pattern in a CAS application's architecture?

Answer: To stop cascading failures by halting calls to a failing downstream service

The circuit breaker opens when a downstream service fails repeatedly, preventing the calling service from wasting resources on doomed requests.

Which metric best measures the actual user-perceived performance of a CAS web application?

Answer: Time to first meaningful paint (FMP)

Time to first meaningful paint measures when users see actionable content, directly reflecting their perception of how fast the application loads.

In CAS performance optimization, what is the primary goal of database connection pooling?

Answer: To reuse existing connections instead of creating a new one for every request

Connection pooling maintains a set of open connections that requests borrow and return, eliminating the overhead of creating and tearing down connections per request.

A CAS application log shows frequent OutOfMemoryError exceptions. What is the most likely root cause?

Answer: Objects are being created faster than they are garbage collected or heap size is misconfigured

OutOfMemoryError occurs when the heap is exhausted, either due to a leak retaining objects or because the heap allocation is too small for the workload.

Which approach best reduces I/O wait time when a CAS application writes large volumes of log data?

Answer: Buffering log writes and flushing asynchronously in batches

Asynchronous batched log writes reduce the frequency of disk I/O operations, freeing the application thread from waiting on each individual write.

What does 'horizontal scaling' mean in the context of CAS application performance?

Answer: Adding more server instances to distribute the load

Horizontal scaling adds more server instances behind a load balancer, distributing traffic across multiple machines to increase total capacity.