gui-unbuffered-retrace (Was: Capture and display frame thumbnails in qapitrace.)

[Dan McCabe]

On 03/26/2012 12:05 PM, José Fonseca wrote:
> On Sun, Mar 25, 2012 at 5:34 PM, José Fonseca<jose.r.fonseca at gmail.com>  wrote:
>> On Sat, Mar 24, 2012 at 11:53 AM, José Fonseca<jose.r.fonseca at gmail.com>  wrote:
>>> On Thu, Mar 22, 2012 at 9:12 PM, Dan McCabe<zen3d.linux at gmail.com>  wrote:
>>>> On 03/22/2012 11:11 AM, José Fonseca wrote:
>>>>> I'm however seeing insane memory usage for large traces. This needs
>>>>> more investigation. But I think that I'l make thumbnailing
>>>>> non-automatic (e.g., menu option) until we address this. This would
>>>>> allow to get this commited in master without causing regressions for
>>>>> the current use cases, and allow to tackle this later (and turn back
>>>>> on by default then).
>>>> The huge memory usage is definitely attributable to thumbnail collection.
>>>> Right now, that collection is simplistic (i.e., **ALL** frame thumbnails are
>>>> captured).
>>> I suspect the problem is not the collection of all frame thumbnails,
>>> but rather QProcess buffering all output (i.e., all uncompressed
>>> frames) until the process finishes. I think the solution is to
>>> refactor Retracer and RetraceProcess classes so that the stdout is
>>> processed while the process is live, and not after.
>>>
>>> I've been reading about QThread, QProcess but I'm not yet confident
>>> enough of the correct way of doing this without inadvertedly
>>> introducing race conditions or Qt threading rule violations...
>> I found a solution for this, by eliminating the QThread event loop,
>> and workaround many quirks in QProcess. I need to do more
>> testing/benchmarking, but this is now in the gui-unbuffered-retrace
>> branch.
> The code looked solid in all platforms, and thumbnail now is fast and
> uses very little memory, so I've merged this.
>
> Jose
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Awesome news! Thanks for looking into this.

cheers, danm