Netprobe Memory Protection Settings

Overview Copied

The Netprobe has memory protection settings that manage its memory resource. Memory protection serves to limit the impact of the Netprobe to the system it is monitoring. Too much memory can cause processes to fail and the system to become unstable. In addition, the Netprobe itself may stop functioning or spontaneously restart.

The checks, variables, and mechanisms mentioned in this guide enable the Netprobe to monitor its own memory in a systematic way, alert the administrator, and protect other components from complications.

The memory discussed in this guide is the Netprobe virtual memory.

Memory checks Copied

The Netprobe has two memory checks:

Maximum memory limit check Copied

The Netprobe checks if its memory has reached a specified maximum limit. If it has, then the Netprobe restarts.

This memory limit is defined by MAX_MEM_SIZE, in megabytes (MB).

The default value for MAX_MEM_SIZE is 0. At this value, the Netprobe does not check if it reaches a certain memory limit.

This check is done every 30 seconds.

This is also applicable to Fix Analyser 2 Netprobe.

Memory growth ratio check Copied

The Netprobe checks if its memory has grown by a specified ratio. If the Netprobe’s starting memory has multiplied by the specified ratio, then it restarts.

By default, the Netprobe checks the memory growth ratio, with the default ratio set to 2. This means that if the memory has doubled, then the Netprobe restarts. For Fix Analyser 2 Netprobe, it is disabled by default.

To enable or disable this check, set DISABLE_MEM_PROTECTION to false or true. To increase the ratio, set MEM_PROTECTION_RATIO between 2 to 5.

Check is done every 10 minutes after a Netprobe starts or restarts.

Initial memory Copied

The MEM_PROTECTION_RATIO setting relies on an initial memory as a baseline. For the Netprobe, this initial memory is captured in the following scenarios:

• When the Netprobe starts or restarts.
• When a sampler configuration is changed.

After the initial memory is recorded, the Netprobe commences its Memory checks.

MEM_UTIL module Copied

The MEM_UTIL module can help you pinpoint the exact timestamp for when a Netprobe records its initial memory.

When you set the MEM_UTIL as a debug option on a probe, the following lines appear on the log:

The first line indicates that the initial memory has been calculated.

The second line indicates that the memory growth has been checked.

Memory protection variables Copied

The Netprobe has memory protection variables that govern its memory checks. These variables can be updated on the Netprobe accordingly:

• On Windows platforms, these variables are set in the registry.
• On non-Windows platforms, these variables are set as environment variables in the shell from which the Netprobe is launched.

For general information on Netprobe variables, see Netprobe variables.

Warning

Do not change these variables in a live environment without first consulting with ITRS Client Services. Inappropriate values can adversely impact the operation of your system.

To know more about the variables that you can set in Netprobe, see Netprobe variables.

Example scenarios Copied

The following table shows different scenarios and how the Netprobe behaves based on its memory protection settings.

All scenarios assume a default MEM_PROTECTION_RATIO of 2. MAX_MEM_SIZE examples values are given to show the behaviour at default, when set at a positive value, and when not set.

Further reading Copied

If you would like to set up memory debugging on the Netprobe, see Netprobe Memory Debugging.