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Negative bandwidth measurements

I've been running boomerang for several days and have been trying to make sense of the data it's been returning.

There seem to be a reasonable number of cases where the 'bw' value is a negative integer. How can this be? It seems that the maximum value of an integer in Javascript should be big enough. I'm logging values to a file with PHP, and I've made it a string value so as to make sure that there's no overflow happening in PHP.

Is there any legitimate reason that these values could be occurring? It's happening at such a volume that I don't suspect that it's malicious.

Thanks

by
5 Replies
  • Can you reproduce this in your own tests or is it only from users? Is there any pattern to the IP addresses that these negative values come in from?

    The only case I can think of where bandwidth would end up negative is if it took less time to download the bandwidth images than it took to download the latency images.

    Do you have the access logs for the bandwidth and latency image request from these IPs?
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  • Thanks for your reply. Here's one example:

    boomerang data:

    {"t":1288757417,"ip":"203.221.167.51","bw":"-947105","lat":458,"bw_err":1339816.6,"bw_time":1288757417,"lat_err":5.66,"u":"http:\/\/www.example.com\/the\/page.html","r":"http:\/\/www.example.com\/the\/page.html","t_content":13711}

    the 'u' and 'r' fields were the same. not sure why that would be...

    access logs (last 3 fields are http status code, response size, time taken to serve the request (ms))

    [03/Nov/2010:04:10:05 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574045740.5569048064242101 http://www.example.com/the/page.html 200 35 1832
    [03/Nov/2010:04:10:05 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574050730.7992024486483502 http://www.example.com/the/page.html 200 35 2103
    [03/Nov/2010:04:10:06 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574055420.8539368589212307 http://www.example.com/the/page.html 200 35 1993
    [03/Nov/2010:04:10:06 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574059950.6417267448805118 http://www.example.com/the/page.html 200 35 1843
    [03/Nov/2010:04:10:07 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574064630.07198443137226862 http://www.example.com/the/page.html 200 35 1887
    [03/Nov/2010:04:10:07 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574069320.25019707563694443 http://www.example.com/the/page.html 200 35 1837
    [03/Nov/2010:04:10:08 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574074000.37826773930990415 http://www.example.com/the/page.html 200 35 2031
    [03/Nov/2010:04:10:08 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574078530.09068966191807898 http://www.example.com/the/page.html 200 35 1907
    [03/Nov/2010:04:10:09 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574083370.30721235064485264 http://www.example.com/the/page.html 200 35 1992
    [03/Nov/2010:04:10:09 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-l.gif ?t=12887574089460.4906671119342544 http://www.example.com/the/page.html 200 35 2088
    [03/Nov/2010:04:10:10 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-0.png ?t=12887574094150.6367880350289462 http://www.example.com/the/page.html 200 11483 2009
    [03/Nov/2010:04:10:11 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-1.png ?t=12887574098670.8848219010511498 http://www.example.com/the/page.html 200 40658 1873
    [03/Nov/2010:04:10:13 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-1.png ?t=12887574124130.8485081845761018 http://www.example.com/the/page.html 200 40658 1898
    [03/Nov/2010:04:10:17 +0000] GET HTTP/1.1 /perf.html ?v=0.9&u=http%3A%2F%2Fwww.example.com%2Fthe%2Fpage.html&r=http%3A%2F%2Fwww.example.com%2Fthe%2Fpage.html&r2=http%3A%2F%2Fwww.example.com%2Fsearch.html&t_other=t_content%7C13711&bw=-947105&bw_err=1339816.6&lat=458&lat_err=5.66&bw_time=1288757417 http://www.example.com/the/page.html 204 0 35299
    [03/Nov/2010:04:10:14 +0000] GET HTTP/1.1 /js/yahoo-boomerang-545b81f/images/image-2.png ?t=12887574137710.8598977735329365 http://www.example.com/the/page.html 200 164897 6317423

    i'll check my logs to see whether this only happens on pages where the url and referrer are somehow the same.

    thanks
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  • QUOTE (San @ Nov 3 2010, 02:06 AM) <{POST_SNAPBACK}>
    i'll check my logs to see whether this only happens on pages where the url and referrer are somehow the same.


    no, this isn't only happening where 'u' and 'r' are the same. and 't_done' seems to be set more often than not.
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  • QUOTE (San @ Nov 3 2010, 02:15 AM) <{POST_SNAPBACK}>
    no, this isn't only happening where 'u' and 'r' are the same. and 't_done' seems to be set more often than not.


    This may need some more thought. Apologies for the delay in replying.
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  • i've just noticed that there's no t_done for this boomerang data. i'm not sure why that is. it sometimes appears.

    t_content is a timer I set up to time only our content, and t_done includes the adverts and other third-party components on our pages.
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