Configure memory overload protection
Follow these instructions to configure memory overload protection from the console.
Read about configuring the autonomic request flow manager.
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.
Avoid trouble: To ensure the memory overload protection to be configured properly, the -agentlib parameter needs to be set in the Generic JVM arguments field.gotcha
To enable, follow these steps from the console:
- Expand Operational policies > Autonomic managers > Autonomic request flow manager.
- Type a value less than 100 in the Memory overload protection: Maximum percentage of the WAS maximum heap size to use field. Click OK.
- Configure the Generic JVM arguments in the Java Virtual Machine settings:
- (dist) Go to Servers > All servers > server_name > Java and process management > Process definition. Click Java Virtual Machine. In the Generic JVM arguments field, set -agentlib:HeapDetect for 32-bit platforms or -agentlib:HeapDetect64 for 64-bit platforms.
- (zos) Go to Servers > All servers > server_name > Java and process management > Process definition > Control . Click Java Virtual Machine. In the Generic JVM arguments field, set -agentlib:HeapDetect for 31-bit platforms, or -agentlib:HeapDetect64 for 64-bit platforms.
- (zos) Go to Servers > All servers > server_name > 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.
Related concepts
Memory overload protection
Related tasks
Configure the autonomic request flow manager
Intelligent Management: autonomic request flow manager custom properties