Execute in main thread example

import maya.cmds as cmds
import maya.utils as utils
import threading

# The thread object used to call your function
class DoLsThread(threading.Thread):
   def __init__(self, func):
      threading.Thread.__init__(self)
      # The function you want to call from Maya
      self.function = func
   def run(self):
      utils.executeInMainThreadWithResult(self.function)

# This is your fucntion
def doLs():
   print cmds.ls(selection=True, objectsOnly=True, long=True, transforms=True)

# Create and run your thread
mythread = DoLsThread( doLs )
mythread.start()

References

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