JMeter Http Request connect timeout forever

Question

I'm using JMeter to test Spring Boot REST API server.

JMeter options are

Concurrent users : 200
Ramp-up period : 10 seconds
Loop Count : 500

The test going well until 1-20000 requests,

but please see next images.

Average response time is below 10ms, but sometimes over 20~50ms.

When response time increases, connect timeout occurrs.

Even if I set the connect timeout over 10 minutes.

Why this error occurred? I can't find it..

Answer 1

As per ConnectTimeoutException documentation:

A timeout while connecting to an HTTP server or waiting for an available connection from an HttpConnectionManager.

So there are 2 possible reasons:

1. Your server fails to process the incoming connections, it might be due to:

   • Incorrect connection pool configuration , amend the settings to match your load pattern
   • Lack of resources, use JMeter PerfMon Plugin to monitor whether the server has enough headroom to operate in terms of CPU, RAM, Network sockets, etc.
   • Inefficient algorithms or bugs in your API implementation, use a profiler tool to see where and why your application spends > 10 minutes before /instead of responding

2. JMeter doesn't have enough resources in order to conduct the required load

   • Make sure to follow JMeter Best Practices
   • If it's not enough - consider switching to distributed testing mode