On 12/25/2016 02:15 PM, Konstantin Tokarev wrote:
25.12.2016, 08:50, "Phil Bouchard" <[email protected]>:
On 12/25/2016 12:25 AM, Konstantin Tokarev wrote:
Greetings,
I am a QML developer and it came to my attention that the animation is
sluggish because of the internal garbage collector.
Do you have any proofs that GC is to blame here?
My app works fine below a certain threshold but as soon as I reach a
certain level of complexity, the animation of the app randomly starts
skipping frames.
Could you please provide self-contained example of application that invokes
pathological GC behavior?
I cannot share my proprietary code but I'll work on some simple example
this week. Basically it consists of having a "Flipable" object inside a
complex Delegate object of a ListView. The Flipable animation skips
frames and the animation is not smooth.
I know the GC randomly kicks in so it fits the same pattern.
Having 2 randomly repeating events in the system does not necessary mean these
events are correlated. You should provide profiling results or at least logs
that show GC kicking in during animation.
I'll try to find out how to turn on GC logging.
I know about the
QtQuickCompiler that could speed up the rendering but it still uses a
garbage collector.
I wrote myself a "container-oriented deterministic memory manager"
called "root_ptr" that could definitely speed up animation of QML objects:
https://github.com/philippeb8/root_ptr
Any numbers for "definitely speed up"?
Well as you can see on the aforementioned link, root_ptr is as fast as
the best usage of shared_ptr but detects cycles and uses the same amount
of memory per pointer.
Decently implemented GC can be faster than shared_ptr, because reference
counting churn is avoided
A GC might be faster at some point but you're just postponing the
workload to some other point in time. So benchmarks need to be
objective. Also a GC needs not use a dedicated thread (which most of
them use) just to be fair in the benchmark.
BTW, FAQ says that VS2015 is required to build your code, so it cannot be
integrated into V4 until VS2013 support is dropped.
I am sorry for this but this FAQ was copied from a template and this
statement is false. It was tested using GCC and portable code is one of
the mantra of the Boost library.
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