Changes between Initial Version and Version 2 of Ticket #1953


Ignore:
Timestamp:
02/05/2015 03:46:41 PM (5 years ago)
Author:
trev
Comment:

Ads count and hit count shall not differ significantly for same filter across different browsers.

That's a wrong expectation. The browser internals are sufficiently different that this isn't true.

The culprit in this particular case is speculative parsing, a feature available starting with Firefox 3.5. Here are some details on it, but the essence is this: while Firefox is stuck processing a script, it will already try to download these images - just in case (that's the speculative parsing). These downloads are blocked by Adblock Plus and counted as hits. Then the script processing finishes and the browser gets to these images by regular means. Given that they haven't been downloaded before, it tries to download them again - and we block them again. As far as Adblock Plus is concerned, these are two separate download actions and each of them has to be counted.

Note that originally I was unable to reproduce the issue, simply because I had the scripts in question blocked.

Legend:

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  • Ticket #1953

    • Property Status changed from new to closed
    • Property Component changed from Unknown to Adblock-Plus-for-Firefox
    • Property Resolution changed from to invalid
  • Ticket #1953 – Description

    initial v2  
    33Windows + Vista 64bit + Firefox + English 
    44ABP version Adblock Plus 2.6.7.3895 
    5  
    65=== How to reproduce === 
    7  
    86Firebox Browser. 
    9  
    1071. Open Firefox Browser with ABP enabled  and load page 
    118http://www.skype-emoticons.com/country-flags.htm 
     
    14113. Refresh the page and flags are blocked 
    15124.  Open filter preferences and check  hit count for png image filter rule. 
    16  
    1713Now Repeat the same on Chrome Browser  
    18141.  Open Chrome Browser with ABP enabled  and load page   
     
    21173. Refresh the page and observe. 
    22184  Check ads count on ABP icon. 
    23  
    2419See screesnshots for both. 
    25  
    26  
    2720=== Observed behaviour === 
    2821Significant difference in Ads blocked/hit count, almost more than 3 times.!!! 
    2922On Firefox : shows 816 hits  whereas 
    3023On Chrome : shows only 243 ads blocked. 
    31  
    3224=== Expected behaviour === 
    3325Ads count and hit count shall not differ significantly for same filter across different browsers. 
    34