[Microbit-Python] Memory leak in print or string formatting

[Damien George]

Thanks for the bug report on this memory error.  I tracked it down to
string data not being zero'd out on initialisation (and hence keeping
a pointer around which prevented the GC from reclaiming some memory,
but in a very pathological way where all previous strings that were
created with str.format were linked in a chain).

A fix will appear soon.

On Thu, Jan 7, 2016 at 12:18 PM, Tom Viner <tom at viner.tv> wrote:
> Yeah I've also had MemoryErrors with .format() too. In my case I was
> formatting floats though.
>
> If it's helpful I can try to find a minimal test case.
>
> As for the memory error, I experimented a bit. Turns out that
> both %- and .format() formatting cause the problem, but not
> necessarily in the same way, e.g. the attached script
> runs fine (at least more than 1000 iterations) when using
> the %-formatting code, but fails with a MemoryError at
> offset 409 with the .format() approach:
>
>         print ('Offset: %i' % offset)
> vs.
>         print ('Offset: {}'.format(offset))
>
> What's interesting is that when you change the display logic
> from:
>
> display_leds = display_leds_set_pixel
>
> to
>
> display_leds = display_leds_image_array
>
> The memory leak appears to go away.
>
> PS: I'm currently experimenting with the fastest way to display
> a list of lists on the LEDs.
>
> Cheers,
> --
> Marc-Andre Lemburg
> eGenix.com
>
> Professional Python Services directly from the Experts (#1, Jan 06 2016)
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