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9. Case Studies > Reverse DNS Lookups Slows Logging

Reverse DNS Lookups Slows Logging

Brian Robinson of Harvard University kindly allowed me to include his account here. Using Netscape Server on Unix, static pages tended not to have any noticeable problem until the thread count maxed out, then had huge delays in the 2-minute range. Server-Side Include (SSI) pages had problems whenever the busy thread count was rising (about a 10-second response time) and were very bad when the thread count maxed out. Response times then seemed to correspond with how long the threads were maxed out—in one case over 15 minutes.

During a bad period, he could see a gradual clogging of Netscape busy threads followed by dramatic clearing from a relatively constant load. The performance of SSI pages was most impacted, and poor performance corresponded closely to the number of busy threads reaching the configured maximum. Performance was also poor when Netscape was allocating more active threads, which it does in chunks. SSI pages normally responded in about 250 ms, but took about 10 seconds when busy thread counts were rising (see Figure 9-2). The performance of static HTML pages was poor only when busy thread count maxed out.


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