Sun Java System Web Proxy Server 4.0.11 Performance Tuning, Sizing, and Scaling Guide
Enabling Statistics
To enable statistics, use Admin Console. 
Note – Collecting statistics causes a slight hit to performance. 
To Enable Statistics (stats-xml) from the
Admin Console
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Select the Proxy Server instance. 
 
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Click the Server Status tab.
 
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Click the Monitor Current Activity sub tab.
 
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Choose Yes for Activate Statistics/Profiling?
 
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Save and apply changes.