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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’ve known about memcached for a while, but only
recently starting researching it for potential implementation within my
company. I love the architecture, but there are two specific issues that
concern me that I haven’t heard have been solved yet:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l1 level1 lfo1'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>1)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>modifying
the server list (to add a new memcached server, for instance) destroys the key
-> server mapping… the equivalent of a flush_all()<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l1 level1 lfo1'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>2)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>connection
pooling<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I realize both of these are not new issues to anyone on the
list. I’ve tried skimming the archives to glean some insight from past
discussions. I found a thread (<a
href="http://lists.danga.com/pipermail/memcached/2006-October/002944.html">http://lists.danga.com/pipermail/memcached/2006-October/002944.html</a>)
that referenced a research paper about consistent hashing. I also found a post
by Brad (http://lists.danga.com/pipermail/memcached/2004-October/000804.html) that
talks about the ‘server list propagation’ problem potentially being
solved by running a set of trackers and using virtual buckets.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Unfortunately, I can’t find anything in the memcached
docs themselves (at danga/memcached/, and in the docs of the PHP and CPAN
modules) addressing these issues, or covering the use of trackers and virtual
buckets, so I suspect that while clever individuals may have come up with
various solutions, none of them have made it into the code.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>So, my questions are as follows:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>1)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>What’s
the current consensus (or nearest to) on the list as to the best strategies for
these two issues? (For the sake of context, assume an apache environment with
mod_perl or mod_php).<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>2)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Are there any
working implementations of these solutions, either as part of the client
libraries, or as additional tools (one of the posts mentioned creating a
memcached admin tool)?<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><span
style='mso-list:Ignore'>3)<font size=1 face="Times New Roman"><span
style='font:7.0pt "Times New Roman"'> </span></font></span></span></font><![endif]><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>If not, can
I help? I’m strongest with Perl, but can hack PHP if need be, and I’m
likely to need both clients at my work. I’m also learning Python, so I’m
up for a good limited-scope project…. I can write good code, but I have
zero experience with memcached to date. So while I’m happy to help, I
don’t think I should be deciding what to implement, or how.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>-ofer<o:p></o:p></span></font></p>
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