Configure memory overload protection
To protect against memory overload, the memory overload protection must initially discover the maximum rate, that is, calls per second, that can be sustained without exceeding the maximum percentage of the maximum heap size. As it is discovering the maximum rate, memory overload protection slowly allows more traffic through without affinity, but will reject the remainder. Initially, a potentially large number of HTTP requests or SIP messages without affinity will be rejected with a 503 (unless the error code is changed). Intelligent Management persists the maximum rate across server restarts, so it must discover the maximum rate once. The maximum rate can change over time due to changes in the session or dialog lifetimes, but these lifetimes generally change relatively slowly and memory overload protection is able to react to such changes. When discovering the maximum rate, Intelligent Management must keep the rate relatively steady for at least an averaging window. The averaging window must be at least as long as the lifetime of most of the HTTP sessions, SIP dialogs, or application sessions. Therefore, the longer the averaging window, the longer it will take to start.
Memory overload protection is disabled by default. Memory overload protection is enabled when the memory overload protection (MOP) value is set to less than 100.
To ensure that the memory overload protection is configured properly, the -agentlib parameter needs to be set in the Generic JVM arguments field. Specifying the -agentlib parameter is only required in WebSphere Application Server v8.5.5.2 and earlier. For a version of WAS after version 8.5.5.2, the -agentlib parameter is always loaded and does not need to be set, even if the autonomic request flow manager (ARFM) is disabled..
Enable memory overload protection
- Expand...
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Operational policies > Autonomic managers > Autonomic request flow manager
- Type a value less than 100 in the field...
- Memory overload protection: Maximum percentage of the WAS maximum heap size to use
Click OK.
- Configure the Generic JVM arguments in the Java Virtual Machine settings:
- Click...
- Servers > All servers > server > Java and process management > Process definition > Java Virtual Machine
In the Generic JVM arguments field, set -agentlib:HeapDetect for 32-bit platforms or -agentlib:HeapDetect64 for 64-bit platforms.
- Click...
- Servers > All servers > server > Java and process management > Process definition > Control > Java Virtual Machine
In the Generic JVM arguments field, set -agentlib:HeapDetect for 31-bit platforms or -agentlib:HeapDetect64 for 64-bit platforms.
- Click...
- Servers > All servers > server > Java and process management > Process definition > Servant > Java Virtual Machine
In the Generic JVM arguments field, set -agentlib:HeapDetect for 31-bit platforms or -agentlib:HeapDetect64 for 64-bit platforms.
- Click...
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