[SailfishDevel] QML arrays and memory leak

Peter Kovacs leginee at gmail.com
Mon May 4 22:51:39 UTC 2015


Hi Kim,

ohh! Okay!

Have you tried splice instead?
Array.prototype.splice (start, deleteCount [ , item1 [ , item2 [ , … ] ] ] )
I think maybe something like:

accarr.splice(0,1,<float>)

Looks more neat and it is in the normal javascript canon. Did not find 
the documentation on javascript and qt quick in the rush.
Hope it helps you as a work around.

Peter

On 04.05.2015 23:08, Kim Foder wrote:
> Hi Peter
>
>> Why use an array and not a vector or an Hash map?
> As far as I know those are not supported under javascript, otherwise a vector
> would have been my first choice, an Hash map is overkill for my needs, I only
> need to add to the end, and always need sequential read.
>
> I am tempted to move the business part to C++, but I'm trying to do as much as
> possible in QML (as an exercise).
>
> /Kim
>
>>   Am 04.05.2015 22:20 schrieb "Kim Foder" <Kim at foder.dk>:
>>> Hi
>>>
>>> For some time I have been battling a memory leak in my pedometer app,
>>> after a
>>> lot of experimentation, I have found the problem to be my use of arrays
>>> (probably)!
>>>
>>> Whenever I receive an acceleration measurement, some statistical
>>> calculations
>>> are made, which results in one float pr. measurement.
>>>
>>> As I need the measurements for a certain time for further statistical
>>> analysis, the results are stored in an array, used as an traveling window
>>> like
>>> this:
>>>
>>> accarr.shift();  // the array is pre-initialized with empty elements.
>>> accarr.push(<float>);
>>>
>>> This works great, but it leaks memory fast, and after some time (between 1
>>> & 2
>>> hours) the OS kills all running apps!
>>>
>>> Any ideas how I can solve this?
>>>
>>> Thanks.
>>>
>>> Kim
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