Putting implementation aside, is LAMP inherently performing worst than commerical alternatives like IIS, ColdFusion, Sun ONE or DB2? Sounds like that's your perposition.
I don't know if there is any number to support this perposition. Note that many largest site have open source components in them. Google, Amazon, Yahoo all run on unix variants. Ebay is the notable exception, which uses IIS. Can you really say ebay is performing better that amazon (or vice versa)?
I think the chief factor that a site performing poorly is in the implementation. It is really easy to throw big money into expensive software and hardware and come out with a performance dog. Google's infrastructure relies on a large distributed network of commodity hardware, not a few expensive boxes. LAMP based infrastructure, if used right, can support the most demanding applications.
LAMP = Linux/Apache/MySQL/P{ython,erl,HP}. Refers to the general class of database-backed web sites built using those components. This being c.l.py, if you want, you can limit your interest to the case the P stands for Python.
I notice that lots of the medium-largish sites (from hobbyist BBS's to sites like Slashdot, Wikipedia, etc.) built using this approach are painfully slow even using seriously powerful server hardware. Yet compared to a really large site like Ebay or Hotmail (to say nothing of Google), the traffic levels on those sites is just chickenfeed.
I wonder what the webheads here see as the bottlenecks. Is it the application code? Disk bandwidth at the database side, that could be cured with more ram caches or solid state disks? SQL just inherently slow?
I've only worked on one serious site of this type and it was "SAJO" (Solaris Apache Java Oracle) rather than LAMP, but the concepts are the same. I just feel like something bogus has to be going on. I think even sites like Slashdot handle fewer TPS than a 1960's airline reservation that ran on hardware with a fraction of the power of one of today's laptops.
How would you go about building such a site? Is LAMP really the right approach?
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