<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Sorry, didn't realize it wouldn't find the context - see below.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Hi,</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">We've been experiencing the exact same issue, although our only difference is that we're only opening the memcached connection once, prior to forking using pctnl_fork.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">I was wondering if you'd had any joy finding a resolution to this - we're currently working on the basis of storing everything in memcached within a one-keyed array, where the key is the same as the memcached key, and the value the same as the value to be stored, and we're then checking the key of the returned array against the requested key from memcached, and if it's wrong, trying again. While this resolves the issue insofar as it prevents us from having the wrong data in the wrong place, it's obviously far from ideal due to the overhead of having to do multiple requests in the case of failure, and of having to check a key value after every get.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Anyway - even if you don't have a solution, it isn't just you having this issue.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Thanks,</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Maxwell</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">************************************************************************</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Hi,</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Since you actually fork the process there should be no possibility of</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">sharing memory between children. And since the connection is established</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">after the fork no sockets are shared, in which case you would probably</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">get data corruption errors instead of a whole object being swapped.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Also, the client doesn't use any globals and works fine under ZTS (the</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">thread safe PHP build).</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">If you have a short script that reproduces the problem, I'd be glad to</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">give it a try and see if I can hunt down the problem.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">//Mikael</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 13px/normal Courier; min-height: 16px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">Kenner Stross wrote:</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> There appears to be a re-entrancy issue with the PHP client. Here's a</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> brief recap of my situation:</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> I have a daemon process that is written in php (and is thus called like</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> this: "php -e myDaemon -- -paramOne -paramTwo &"). Once it is launched,</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> it follows standard daemon coding practices to set itself up as a</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> detached session leader and wait for something to do. Once there is</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> something to do, it will fork some children to do the work. Looks like</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> this:</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> myDaemon (the parent, which forks three times in this example)</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> <span class="Apple-tab-span" style="white-space:pre"> </span>myDaemon (child 1)</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> <span class="Apple-tab-span" style="white-space:pre"> </span>myDaemon (child 2)</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> <span class="Apple-tab-span" style="white-space:pre"> </span>myDaemon (child 3)</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> The memcache client is not instantiated until the children have forked,</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> so that each child can have a memcache client that is separate from and</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> unrelated to the other children. However, it appears that they are all</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> still intertwined at some deeper level, apparently as a result of having</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> forked out of the same php process space (I guess).</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> The symptoms are this: At various random points, a memcache "get" for</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> object1 (whose type is class1) will return object2 (whose type is</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> class2). In other words, it is returning the wrong objects. To me,</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> this sure looks like a reentrancy problem, where one child is being</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> swapped in by the processor at JUST THE RIGHT MOMENT to pick up the</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> OTHER OBJECT from the OTHER CHILD that was just swapped out.</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> The confirmation that this is the problem is that when I set a limit</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> such that the parent can never fork more than one child, the problem</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> goes away. Handled that way, memcache always returns the correct</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> object.</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> Has anybody had similar experiences? I'd love to hear what others may</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> know about this issue and/or the architecture of the php client</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> vis-a-vis forking.</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> Thanks,</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> Kenner Stross</i></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Courier" size="4" style="font: 13.0px Courier">><i> </i></font></div><div> </div><br></body></html>