GitHub Copilot – Real-World Java Backend Engineering Model Evaluation
Compare AI models for Java/Spring development across fast coding, debugging, bug fixing, legacy codebase analysis, story impact assessment, concurrency performance, and source-grounded technical documentation. Evaluate correctness, speed, reasoning quality, minimal changes, and reliability.
Prompt
A traditional Spring MVC application on Java 17 handles 100 requests/sec. Each request invokes CompletableFuture.supplyAsync() without an explicit Executor; its supplier performs a blocking HTTP call with a mean latency of 400 ms and p95 latency of 1.5 seconds. The host reports 8 available processors. During load, response latency spikes, but CPU usage remains below 40%. Diagnose the most plausible causes, explain ForkJoinPool.commonPool behavior, propose measurements to distinguish hypotheses, and recommend specific mitigations. Do not assume thread starvation has already been proven. Distinguish average concurrency from p95 capacity requirements.
Answer guidance
Expected: Little's Law gives ~40 average concurrent calls; blocking work on the common pool is risky; account for actual common-pool parallelism/configuration, queued work, and blocked threads. Include measurements, explicit I/O executor/bounds, timeouts, rejection policy, and alternatives. Do not present 40 as p95 capacity.
OpenAI
Response not available
OpenAIOpenAI
Google