Remember that Hystrix could not be queued for execution and no fallback available when calling Feign for a pressure test.

Project scenario:

Feedback from colleagues during stress testing only supports 10 concurrent users

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Problem Description

通过查看日志，可以看到一下关键报错信息：
could not be queued for execution and no fallback available.

Cause Analysis:

Hystrix默认是10个线程，超过就会报这个异常（线程池的拒绝策略）

solution:

Modify the Hystrix configuration, the problem is solved, as follows:

hystrix:
  threadpool:
    default:
      coreSize: 200 # 并发执行的最大线程数，默认10
      maxQueueSize: 200 # BlockingQueue的最大队列数
      queueSizeRejectionThreshold: 50 # 即使maxQueueSize没有达到，达到queueSizeRejectionThreshold该值后，请求也会被拒绝
      execution:
        timeout:
          enabled: true
        isolation:
          strategy: THREAD
          semaphore:
            maxConcurrentRequests: 1000
          thread:
            timeoutInMilliseconds: 30000