uasyncio: cancel a task which is running inside a task

[rootfrogsMakes]

Hello,
I deep dived a little bit into multi tasking with uasyncio. I am observing behaviour that I cannot explain.
Maybe some one know whats going wrong?

To show the issue more easy I wrote a small example:

import uasyncio

async def myPrinter():
    global subTask
    while(True):
        print("== Printing now ==")
        subTask = uasyncio.create_task(subPrinter())
        try:
            await uasyncio.wait_for(subTask, 10000)
        finally:
            print("Subtask finished")
        print("== Printing finished ==")
		
async def subPrinter():
    for i in range(7):
        print("sub print")
        await uasyncio.sleep_ms(500)

async def mainLoop():
    global subTask
    printerTask = uasyncio.create_task(myPrinter())
    await uasyncio.sleep_ms(2000)
    print("Its time to stop subPrinter...")
    subTask.cancel()
    print("SubPrinter is stopped")
    await uasyncio.sleep_ms(10000)
    print("Program is finished")

uasyncio.run(mainLoop())

So I start a printerTask with function myPrinter. Inside the printerTask I create a subTask. Its Task-Object is global.
In the Main loop I now try to stop the subTask by calling subTask.cancel(). The task cancels (instead of 7 times printing "sub print", It just prints it 4 times) and I get the printout "Subtask finished".
However, not only the subTask is cancelled, but also the printerTask. The finally statement which prints out "Subtask finished" gets called, but the command after it with the printout "== Printing finished ==" isn't called. So it seems that the printerTask also get cancelled.

Why can't I just stop the subTask? Is it possible to cancel just the subTask and keeps the printerTask running?

Output of the program above:

== Printing now ==
sub print
sub print
sub print
sub print
Its time to stop subPrinter...
SubPrinter is stopped
Subtask finished
Program is finished

[ned-pcs]

Add another try/except:

async def myPrinter():
    global subTask
    while True:
        print("== Printing now ==")
        try:
            subTask = uasyncio.create_task(subPrinter())
            try:
                await uasyncio.wait_for(subTask, 10000)
            finally:
                print("Subtask finished")
            print("== Printing finished ==")
        except uasyncio.CancelledError:
            print("Subtask cancelled")

On my system (using the Linux build of Micropython) I get this output:

== Printing now ==
sub print
sub print
sub print
sub print
Its time to stop subPrinter...
SubPrinter is stopped
Subtask finished
Subtask cancelled
== Printing now ==
sub print
sub print
sub print
sub print
sub print
sub print
sub print
Subtask finished
== Printing finished ==
== Printing now ==
sub print
sub print
sub print
sub print
sub print
sub print
sub print
Subtask finished
== Printing finished ==
== Printing now ==
sub print
sub print
sub print
sub print
sub print
sub print
Program is finished

[rootfrogsMakes]

Oh, thanks for the hint.
You are right, I forgot the except statement. It also works if I change the finally statement to an except path:

async def myPrinter():
    global subTask
    while(True):
        print("== Printing now ==")
        subTask = uasyncio.create_task(subPrinter())
        try:
            await uasyncio.wait_for(subTask, 10000)
        except:
            print("subtask exception")

Due to the missing exception handling for the subTask, the uasyncio.CancelledError will affect the printerTask too. But if I handle it, the printerTask keeps running.

Thank you for the idea.