Workers framework doesn't allow system tasks to make progress

[anicolao]

By default, the workers framework never releases control to micropython, so system services stop working.

For example, I have a board which has both wired ethernet and wireless. If I run a web server on the wired interface using socket callbacks, it works fine. But if I then load the mesh networking example which uses the workers framework, all execution is in the application code and the socket callbacks for my webserver never happen.

Simply hacking the mesh code to occasionally call time.sleep(1) creates the opportunity for the system to trigger the socket event handlers, and makes my webserver "work", but very slowly (or more precisely, at some frequency depending on how often my sleeping worker comes up in the round robin of the cooperative scheduling).

I think a better fix might be to somehow yield to the core micropython interpreter inside the loop in worker.py between cooperative tasks. My understanding of the code is limited, but perhaps at the top of the loop just before the send would be a reasonable spot:

   def start(my):
      i=0
      while K.tail>0:
         ## HERE - yield to the micropython interpreter
         time.sleep(0)
         ## schedule the next task
         C=K.A[i]
         try:
            w=C.send(my.s)
         except StopIteration:
            w=True # Done
         except Exception as x:
            w=False # Error
            my.x=str(C).split()[2]+' '+str(x)
         if w!=None:
            C.close();del C
            #gc.collect()
            K.tail-=1
            if i==K.tail: i=0
            else: K.A[i]=K.A[K.tail]
            K.A[K.tail]=nop
         else:
            i+=1
         if i>=K.tail:i=0
      return

So a few problems with this fix:

1- I am not sure if time.sleep(0) will work as intended or is even the right way to give the system control; and
2- I am not sure if this is really teh right spot in worker.py

[anicolao]

In my testing, this fix works. Using utime.sleep_us(1) did not work. A proper fix would be great, but this patch is good enough for me.