Permanent pread of history.hash file

Russ Allbery rra at stanford.edu
Thu Jul 10 20:24:30 UTC 2008


Sebastian Wiesinger <inn at tracker.fire-world.de> writes:

> While transferring my articles from one INN to another, I noticed that
> the new innd almost permanently does a pread on the history.hash file.
>
> This didn't stop after the transfer was finished, and is still
> happening. Both systems run Debian 4.0 with inn 2.4.3. The old system
> was a 32bit system, the new one is an amd64 x86_64 system.
>
> This was not happening with the old innd.
>
> strace'ing the new inn gives constant preads like this:
>
> pread(13, "\220\20470\3t", 6, 44838060) = 6
> pread(13, "\241\32:;\315\362", 6, 44838066) = 6
> pread(13, "\331\214\246D\177A", 6, 44838072) = 6
> pread(13, "P\201\363\254\271\345", 6, 44838078) = 6
> pread(13, "\34m\201Fr;", 6, 44838084)   = 6
> pread(13, "\226\266f\334\335t", 6, 44838090) = 6
> pread(13, "\356\33\253\355\301\33", 6, 44838096) = 6
> pread(13, "\324c\24\223\332\347", 6, 44838102) = 6
> pread(13, "\345\3773b\n%", 6, 44838108) = 6
> pread(13, ")w\214\231\207\236", 6, 44838114) = 6

This is a wild guess, but if you had a history database that was sized way
too small for the number of articles you were storing, you would have
gotten multiple bucket and hash table overflows and each hash lookup will
be very, very slow and will end up reading all over the place in the
history file.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>

    Please send questions to the list rather than mailing me directly.
     <http://www.eyrie.org/~eagle/faqs/questions.html> explains why.


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