Q:

Ramp up period 0 vs 1

What is the difference between ramp up period 1 and ramp up period 0 ?
I have Thread count 10 and while giving ramp up 0 some of my cases making null pointer exception.With ramp up 1 its working fine. With ramp up 1 it means that within 1 second 10 users will start together. What will happen for ramp up 0?

A:

If you set ramp-up as 0, all the threads will start at 1st second after the test has been started.  If the ramp-up period is zero, JMeter will create all the threads at once and send out requests immediately.
You can use it while you require a sudden large influx of requests in your site.
Let's say you have set it up to use 10 threads and have a ramp-up period of 0 then when you start your test run it will make 10 requests at the exact same moment.

