document: A method for transparent admission control and request scheduling in e-commerce web sites This paper presents a method for admission control and request scheduling for multiply-tiered e-commerce Web sites , achieving both stable behavior during overload and improved response times . Our method externally observes execution costs of requests online , distinguishing different request types , and performs overload protection and preferential scheduling using relatively simple measurements and a straight forward control mechanism . Unlike previous proposals , which require extensive changes to the server or operating system , our method requires no modifications to the host O.S. , Web server , application server or database . Since our method is external , it can be implemented in a proxy . We present such an implementation , called Gatekeeper , using it with standard software components on the Linux operating system . We evaluate the proxy using the industry standard TPC-W workload generator in a typical three-tiered e-commerce environment . We show consistent performance during overload and throughput increases of up to 10 percent . Response time improves by up to a factor of 14 , with only a 15 percent penalty to large jobs .
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