Tuning the OMEGAMON Enhanced 3270 user interface for CPU use

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Use this topic to investigate and reduce high CPU consumption in the OMEGAMON® enhanced 3270 user interface (enhanced 3270UI).

Problem description

If the enhanced 3270UI consumes more CPU than expected, the cause is often a combination of periodic background processing and active user session behavior. CPU consumption can increase even when no timeout or error messages are written to SYSPRINT.

Common contributors

The following activities can increase enhanced 3270UI CPU use:
  • Periodic Registry Refresh processing, especially in environments with large numbers of managed system names (MSNs) and managed system lists (MSLs).

    The registry resides within the enhanced 3270UI address space, and it contains a list of all known hub monitoring servers, data retrieval agents (DRAs), OMEGAMON agents, monitored nodes (MSNs), and MSLs. By default, the registry information is automatically refreshed every 5 minutes. When the environment has many MSNs and MSLs, each registry refresh cycle can require more processing time and contribute noticeably to cumulative CPU consumption.

  • Periodic situation status collection for the connected hub monitoring servers.

    The enhanced 3270UI periodically collects situation status for discovered monitoring servers. By default, situation status collection occurs every 5 minutes to keep situation status current for workspace displays. Even when no user is actively navigating a situation workspace, this background collection still performs hub-side requests and result processing in the address space, which adds to baseline CPU use.

  • Real-time situation status collection when users work in situation status workspaces such as KOBSEVTS, press the Enter key, or run workspaces with Auto Update enabled.

    Real-time collection is driven by user activity, so short Auto Update intervals or repeated Enter keystrokes can trigger frequent query cycles. In unattended sessions, these cycles continue until Auto Update is suspended or the session times out, which can cause sustained CPU utilization over long periods.

Auto Update and session timeout considerations

Any workspace that retrieves significant data can increase CPU use when Auto Update is configured with a low interval. This behavior is not limited to one workspace.

If unattended sessions are left active for long periods (for example, overnight or over a weekend), carefully evaluate the session timeout settings specified in the KOB_TIMEOUT parameter.

A timeout value of 0 means that sessions do not time out. A combination of KOB_TIMEOUT=0 and a low Auto Update interval can allow unattended sessions to continue consuming CPU.

How to identify active sources of CPU use

  1. Open the actions menu and select Tools > U Active 3270 Users to review currently logged on sessions and their resource usage (CPU time and storage).
  2. Open the actions menu, and select View > P Session Performance to review SQL1 query performance for the current hub and short-term 3270 session performance history.
  3. For high-activity sessions, check the Auto Update value shown in the upper-right corner of the workspace and identify unattended sessions with short intervals.

Tuning actions

To balance resource consumption and data freshness, consider one or more of the following actions:
  • Increase Auto Update intervals for workspaces with heavier data retrieval, or set Auto Update to off for unattended sessions.
  • Use a nonzero session timeout value when unattended sessions are expected.
  • Increase the Registry Refresh interval when your environment has large registry content.
  • Enable Dynamic (Delta) Registry Refresh if the option is available in your release level. This option helps keep the registry current, especially in cases where the Registry Refresh interval has been increased.

Additional maintenance consideration

Real storage growth can also affect CPU behavior over time. Verify that current APAR and PTF maintenance is applied for the enhanced 3270UI and related monitoring components.