I am using Appium 1.6.3 for automating IOS 10 devices, But don’t know how to do parallel execution. Please help if anybody executed parallel execution of IOS devices using Appium?
No Support… 
But I have done it myself 
@Swapan_Chhabra follow these steps!
- install command line appium
- start two instances of appium with different port e.g. 4723 and 4724
- create two java thread class with static variable port as 4723 and 4724 respectively with run method executing your appium script.
- Start both of the threads.(like wise you may use more threads.)
This is how very basic parallel execution you may achieve.
I achieved this by modifying appium source but it is totally self developed architecture similar to perfecto!
@Swapan_Chhabra welcome! you can even coordinate(swarm of devices) two parallel test cases on multiple devices very easily for multi user applications such as Trading app where you need simultaneous 2 or more users coordination to test some strategy! you just need to have flexible framework architecture and perfect design pattern to support that!