Obscure bug involving AjaxFlexibleFileUpload
Obscure bug involving AjaxFlexibleFileUpload
- Subject: Obscure bug involving AjaxFlexibleFileUpload
- From: Paul Hoadley <email@hidden>
- Date: Mon, 23 Jun 2014 15:43:41 +0930
Hello,
I've been using AjaxFlexibleFileUpload in a project for a few months now, but I've been getting reports of occasional failures. The symptoms are very specific:
1. User clicks "Select File..." and selects a file.
2. User clicks "Upload", and nothing happens.
That is, the expected behaviour at 2 is, obviously, a progress meter appears, and the file is uploaded. What actually happens is the the "Upload" link disappears, but nothing else happens. The "clear" icon remains, and is the only work-around for the issue: the user can clear the selected file and try again, at which point the upload succeeds.
There are some features that make me think this is going to be terrible to track down.
Firstly, it's non-deterministic to the extent that I can't provide a particular file and a finite number of steps that guarantee the problem will exhibit. It's "statistically deterministic", if you like, in that I seem to be able to guarantee that if you make n consecutive upload attempts, you'll see at least m failures. 15 seems to be about the number for n, and then m varies between about 1 and 7 depending on some other things...
Secondly, it's not limited to one browser. You'd think this was a good sign (in that it might be a fixable bug in the component rather than the browser), except that m above (the number of failures you see in, say, 15 attempts) appears to vary across browsers. In Firefox, it's about 7. In Safari, it's more like 1-3. There may well be nothing in that, I'd have to run more tests. There's no useful output on the console of any browser when the UI fails as described.
Thirdly, it seems to vary according to how heavily the component is styled. We've got some semi-hairy styling going on for that component. Firefox will go from about 7 errors per 15 attempts down to 0-1 per 15 attempts if I pull the styling.
Before I invest too much time into it, has anyone seen anything like this using AjaxFlexibleFileUpload, or are people finding it 100% reliable? To be sure, I've created a trivial test app containing AjaxFlexibleFileUpload, and it works without failure. But in the real world, there's a lot more going on in the page, and maybe this component is a little delicate. (I'm pulling things off the page one by one, but no joy yet.) Can anyone shed any light on this with real world experience with AjaxFlexibleFileUpload?
--
Paul Hoadley
http://logicsquad.net/
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