Solace Memory Test

In general, the physical memory of the Solace PubSub+ Event Broker should not be oversubscribed and should not be backed by swap. Under stress, the Solace PubSub+ Event Broker may make extensive use of swap memory in addition to the physical memory.

Solace subscriptions consume memory resources based on the number of active subscriptions and the complexity of the topic hierarchy. When a message broker handles subscriptions, the broker should maintain an internal data structure called a subscription cache or subscription tree to efficiently match incoming messages with subscribers.

The memory usage of Solace subscriptions depends on the following factors:

• Number of Active Subscriptions: The memory usage increases with the total number of active subscriptions. Each subscription typically requires a certain amount of memory to store its state and associated metadata.

• Topic Hierarchy Depth: If your subscription topics have a deep hierarchy, with many levels of subtopics, it can increase memory consumption. This is because the subscription tree needs to maintain the hierarchical structure to enable efficient matching of messages to subscribers.

• Wildcard Subscriptions: If wildcard subscriptions are used, such as using the "*" or ">" wildcards in the topics, it can potentially increase memory usage. Wildcards introduce additional complexity in the subscription matching process and may require more memory to store wildcard-based subscriptions.

• Subscription Durability: Solace supports durable subscriptions, which allow subscribers to receive messages even if they temporarily disconnect. The memory usage will be influenced by the number of durable subscriptions since the broker needs to retain the state of each durable subscription until it is explicitly deleted or expires.

If the usage of swap memory is alarmingly increasing or if the memory resources allocated for Solace subscriptions is exhausted, then, the target broker may not be consistent in storing data and matching the incoming messages with the subscribers. To proactively ascertain any memory related issues and rectify them at the earliest, administrators can use the Solace Memory test.

This test enables administrators to track the memory usage (physical memory, swap memory and memory allocated for subscriptions) of the target Solace PubSub+ Event Broker. This way, administrators can ascertain if the target broker is memory-hungry and if so, allocate additional memory resources so that the target event broker has more memory at its disposal. By merely looking at the measures reported by this test, administrators can figure out which type of memory is being over-utilized - is it physical memory? or swap memory? or the memory allocated for Solace subscriptions?

Target of the test : A Solace PubSub+ Event Broker

Agent deploying the test : A remote agent

Outputs of the test : One set of results for the Solace PubSub+ Event Broker that is being monitored.

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	The IP address of the target host for which this test is to be configured.
Port	Refers to the port at which the Solace PubSub+ Event Broker listens to.
UserName and Password	By default, the eG agent executes SEMP ( Solace Element Management Protocol) APIs on the target broker to collect the required metrics. For the eG agent to execute the SEMP APIs, a special user with read only privilege is required. Specify the credentials of such a user in the UserName and Password text boxes. To know how to create such a user, refer to Creating a New User for Monitoring Solace PubSub+ Event Broker.
Confirm Password	Confirm the Password by retyping it in the Confirm Password text box.
SSL	By default, this flag is set to No indicating that the Solace PubSub+ Event Broker is not SSL-enabled by default. Set this flag to Yes if the Solace PubSub+ Event Broker is SSL-enabled.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Total physical memory	Indicates the total physical memory of the target event broker.	GB
Used physical memory	Indicates the amount of physical memory that is already utilized on the target event broker.	GB	A value close to Total physical memory measure is an indication that the target event broker is running out of physical memory. Administrators need to allocate additional physical memory so that the target event broker remains operational.
Free physical memory	Indicates the amount of physical memory that is available for use in the target event broker.	GB	A high value is desired for this measure.
Buffered memory	Indicates the amount of physical memory that is allocated as buffer memory in the target event broker.	GB
Cache memory	Indicates the amount of physical memory that is cached in the target event broker.	GB
Physical memory usage	Indicates the percentage of memory that is already utilized by the target event broker.	Percent	A value close to 100 percent indicates that the target event broker is running out of physical memory.
Total swap memory	Indicates the total swap memory allocated for the target event broker.	GB
Used swap memory	Indicates the amount of swap memory that is already utilized on the target event broker.	GB	A value close to Total swap memory measure is an indication that the target event broker is running out of swap memory.
Free swap memory	Indicates the amount of swap memory that is available for use in the target event broker.	GB
Swap memory usage	Indicates the percent of swap memory that is already utilized by the target event broker.	Percent	A value close to 100 percent indicates that the target event broker is running out of swap memory.
Total subscriptions memory	Indicates the total amount of memory allocated to store Solace subscriptions.	GB
Used subscriptions memory	Indicates the amount of memory utilized by the Solace subscriptions.	GB	A value close to Total subscriptions memory measure is an indication that the target event broker is running out of memory allocated for Solace subscriptions.
Free subscriptions memory	Indicates the amount of memory that is available for use by the Solace subscriptions.	GB
Subscriptions memory usage	Indicates the percentage of memory that is utilized by the Solace subscriptions.	Percent	A value close to 100 percent indicates that the target event broker is running out of memory to store Solace subscriptions.