Appium have problem when running two devices simultaneously

When i tried to run one by one, the device works. But when i ran it simultaneously using testNG, it gives an error on one of the device (randomly). Sometimes it says ECONRESET and sometimes zipalignapk cannot run, where the other device works fine. Thank You in advance :smile:

i have solve the problem by myself, i just add thread.sleep(4000); on one of the device so it will not clash with another device(in my thoery). im using appium 1.3.1.