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PORails 2.2.2 Performance Problem/Bug
 

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  1. PORails 2.2.2 Performance Problem/Bug
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    <p>I recently upgraded one of my applications to Rails 2.2.2. Having done that, I've encountered a strange performance bug that has caused renders that used to complete in a fraction of a second to take up to 10 seconds.</p> <p>I've profiled the issue, and <a href="http://compucatedsolutions.com/~jmc/rails/profile-flat.txt" rel="nofollow noreferrer">here are the results I've come up with</a>. It looks like the issue is in the <code>real_connect</code> method of the Mysql class. My understanding is that the Ruby <code>real_connect</code> method is a wrapper around the C <code>mysql_real_connect()</code> function. This would lead me to believe that the issue must be with the database, since I've encountered the same problem when running the code on Windows and Linux (the database server is a separate system). I don't, however, believe this is the case, because when I roll back to a previous version (pre Rails 2.2.2) from my subversion repository, the performance issue goes away. This would seem the indicate that there is some kind of bug in ActiveRecord.</p> <p>How do I go about identifying and fixing this bug? Does anyone have any insight? Is there something I'm missing?</p> <p><strong>Update: I just created a small profiler script to test the Mysql.real_connect method, and it appears that the problem isn't in Rails, but in the MySQL gem or the database server itself.</strong></p> <p>Upon running the following code:</p> <pre><code>result = RubyProf.profile do 5.times do begin # connect to the MySQL server dbh = Mysql.real_connect(ip, user, pass, db) # get server version string and display it puts "Server version: " + dbh.get_server_info rescue Mysql::Error =&gt; e puts "Error code: #{e.errno}" puts "Error message: #{e.error}" puts "Error SQLSTATE: #{e.sqlstate}" if e.respond_to?("sqlstate") ensure # disconnect from server dbh.close if dbh end end end printer = RubyProf::FlatPrinter.new(result) printer.print(STDOUT, 0) </code></pre> <p>I came up with this performance result:</p> <pre><code>Server version: 5.0.32-Debian_7etch3-log Server version: 5.0.32-Debian_7etch3-log Server version: 5.0.32-Debian_7etch3-log Server version: 5.0.32-Debian_7etch3-log Server version: 5.0.32-Debian_7etch3-log Thread ID: 18998180 Total: 50.402000 %self total self wait child calls name 99.99 50.40 50.40 0.00 0.00 5 &lt;Class::Mysql&gt;#real_connect (ruby_runtime:0} 0.00 0.00 0.00 0.00 0.00 10 IO#write (ruby_runtime:0} 0.00 0.00 0.00 0.00 0.00 5 Mysql#get_server_info (ruby_runtime:0} 0.00 0.00 0.00 0.00 0.00 5 Kernel#puts (ruby_runtime: 0} 0.00 0.00 0.00 0.00 0.00 5 String#+ (ruby_runtime:0} 0.00 0.00 0.00 0.00 0.00 5 Mysql#initialize (ruby_runtime:0} 0.00 50.40 0.00 0.00 50.40 1 Integer#times (ruby_runtime:0} 0.00 50.40 0.00 0.00 50.40 1 Global#[No method] (tmp/mysql_test/test.rb:12} 0.00 0.00 0.00 0.00 0.00 5 Mysql#close (ruby_runtime: 0} </code></pre> <p>It seems as though the problem isn't in ActiveRecord, it's either in the MySQL gem or in the database. Where do I go from here?</p>
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