Python SimpleActionServer stops unexpectedly (deadlock!)

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Hi all,

I'm writing a small piece of code that leverages actionlib, specifically SimpleActionServer. The main intricacy is that I register a preempt callback, but then I set_preempted on another thread (see code below).

However, when the rate of requests is relatively high (~1Hz) sometimes actionlib stops processings new requests. It does not crash, it does not print nor log anything, it just idles.

Below is a simplified version of my code:

class Node():

    def __init__(self):   
        self.server = actionlib.SimpleActionServer(
            "Topic", 
            Action,
            execute_cb=self.run,
            auto_start=False )

        #Variables so that preemption works
        self.myLock = threading.Lock()
        self.taskID = None

        #register preempt callbacks
        self.server.register_preempt_callback( self.stop )

        #Start actionlib
        self.server.start()


    def run(self, goal):      
        with self.myLock:
            self.taskID =  startTask() #Launch task in another thread

        #Wait for task to be completed or killed
        if not (self.taskID is None):
            wait( self.taskID ) #Wait for task to finish

        #Do not allow task to be preempted from now
        with self.myLock:
            self.taskID = None

        # Get actionlib result
        result = ActionResult()
        getResult(result)

        if not valid(result): #valid() defined elsewhere
            self.server.set_aborted( result )        
        elif self.server.is_preempt_requested() :
            self.server.set_preempted( result )
        else :
            self.server.set_succeeded( result )

        # Sometimes actionlib will stop processing new requests after this!!


    def stop( self ):
        with self.myLock:
            if ( not ( self.taskID is None ) and self.server.is_preempt_requested() ):
                killTask( self.taskID ) # Function defined elsewhere
                self.taskID = None

Am I using actionlib in an invalid way? Could this be an actionlib bug?

Thanks, Miguel S.