<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Hi!</div><div><br></div><div>Interesting question.</div><div><br></div><div>If I had to guess, I’d say it’s because our automated testing has improved considerably since 3.5. A number of memory leak finding tools[1] have been integrated into our test environments that are improving our early catch-rate. This is in addition to our ever-expanding set of unittests running on every checkin[2].</div><div><br></div><div>I think your second point ("more than 85% of backouts occurred during or before merging into central”) supports the “better testing” theory. Proving this would be difficult as you’d need to mine all of the backout-related bugs to find the reason for the backout. Searching for keywords like “regression”, “leak” or “fail” might be automatable.</div><div><br></div><div>~ rob</div><div><br></div><div>1- <a href="https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/Debugging_memory_leaks">https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/Debugging_memory_leaks</a></div><div><br></div><div>2- <a href="https://developer.mozilla.org/en-US/docs/Mochitest">https://developer.mozilla.org/en-US/docs/Mochitest</a></div><br><div><div>On Jul 27, 2014, at 11:12 , Rodrigo Rocha Gomes e Souza <<a href="mailto:rodrigorgs@gmail.com">rodrigorgs@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div>As part of my PhD, I've been keeping track of backouts from Firefox 3.5 up to Firefox 27, and I noticed that, since the adoption of 6-week releases, the backout rate (num. of backouts / num. of bugs fixed) has increased from 6.8% to 9.4% [1]. I wonder...</div>
<div><br></div><div>1. ... have you noticed the increase in backout rate or its effects?</div><div>2. ... why would the backout rate grow under rapid release cycles?</div><div><br></div><div>Would you help me with these questions? It's always good to get feedback from people who actually work on Firefox.</div>
<div><br></div><div>Some additional insights:</div><div><br></div><div>* I noticed that, after the adoption of rapid releases, the number of bugs fixed per day increased 74%, but also that the number of developers (computed as the num. of people that committed at least 10 bug fixes) increased 75%, so *apparently* developer workload haven't increased (please correct me if I'm wrong). Therefore, workload doesn't seem to explain the growth in backout rate.</div>
<div>* I also noticed that, under rapid releases, more than 85% of backouts ocurred during or before merging into central (i.e., before the bug status changed to FIXED), versus 55% under traditional releases. Seems like an improvement, since more problems are being discovered during automated testing and less manual tests need to be repeated due to backouts.</div>
<div><br></div><div>[]s</div><div>Rodrigo</div><div><br></div><div>[1]: <a href="http://rodrigorgs.github.io/images/firefox-backouts.png">http://rodrigorgs.github.io/images/firefox-backouts.png</a></div></div>
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