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From:Mike South Date:April 4 2003 1:09pm
Subject:Re: Open_files drops fast. Why?
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>From dan@stripped  Wed Apr  2 17:12:36 2003
>
>In the last episode (Apr 02), Mike South said:
>> In load testing I noticed that, even though all the queries in the
>> tests are for the exact same tables, at some point in the test
>> the Open_files variable  (from SHOW STATUS) drops very quickly.  Does 
>> anyone have any idea what would cause that?  
>
>Each thread opens its own filedescriptors for the tables it uses.  10
>threads accessing 4 tables uses (10 threads * (4 table files + 4 index
>files)) = 80 fds; 100 threads uses 800.

I am reasonably sure that Open_files does not reflect how many threads
are accessing each table.  Just from observation, I see that Open_files
remains pretty constant (except for the drop I mentioned above,
after which it remains constant, just at a lower level), even though 
the number of threads connected/running jumps up and down.  I assume
that the server is keeping references to the files open and handing them
off to threads as needed, or something along those lines.

mike
Thread
Open_files drops fast. Why?Mike South2 Apr
  • Re: Open_files drops fast. Why?Paul DuBois3 Apr
  • Re: Open_files drops fast. Why?Dan Nelson3 Apr
Re: Open_files drops fast. Why?Mike South4 Apr
  • Pre parsingJerry4 Apr
    • RE: Pre parsingNick Arnett4 Apr
    • RE: Pre parsingMichael Shulman4 Apr
Re: Open_files drops fast. Why?Mike South4 Apr