Chapter 9: Using the Performance Monitor  Configuring memory thresholds

Chapter 9: Using the Performance Monitor

How it works

Ideally, an applications request rate relates linearly to response rate as shown in Figure 9-1.

However, performance of any application depends on availability of resources like CPU, memory, network connections, and swap space. These resources are limited, and when they are exhausted, the response rate degrades. Due to resource limits, the response rate is expected to level off when the number of incoming requests reaches the point where resources are exhausted, as shown in Figure 9-2. However, in practice, an unlimited increase in incoming requests can cause performance to degrade; the response rate can drop in this case. In extreme cases, the application may run out of memory and abend or hang.

Figure 9-1: Ideal response rate curve

Figure 9-2: Expected response rate curve

Performance Monitor allows you to configure the system to operate at a constant response rate and avoid out-of-memory conditions under high load conditions. Performance Monitor uses these algorithms to heuristically govern the request rate when high load conditions are detected:

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