Since OpenEdge 11.7.2 and later, a property called
agentStartLimit can be configured to throttle how many agents will be started simultaneously when the Session Manager determines more agents are needed and thereby smooth out the proliferation of agents when PAS dynamic ABL session scaling would otherwise cause a phenomenon referred to as
"Agents Explosion" or an "Agent Storm":
- A sudden burst of new client activity occurs when no agents sessions are available on existing MSAgents (maxConnectionsPerAgent)
- The Session Manager starts a new MSAgent process in response to the request load
- If further new client requests are received during the startup of this new agent, these requests then cause additional new MSAgents to start (since none are available to handle the request).
- This causes a variety issues including MSA crashes, system resource instability. It can happen to a greater or lesser degree, depending on how quickly new agents are started and how quickly client requests are received.
PASOE agentStartLimitDefines the maximum number of MSAgents the Session Manager will start at the same time when more agents are needed based on client load and available
maxConnectionsPerAgent.
When the agentStartLimit value is zero or not defined, then no limit is enforced.
The session manager will start only that value (maximum number of agents to start) and once the startup of that (those) agent(s) is complete, it will then decide if it needs to start more (again based on client load and maxConnectionsPerAgent). In so doing it will not try to start too many new MSAgents to meet the load request demand when it takes too long to start the new agent.
Configuration needs to be done in the
openedge.properties file or from
OEM for a given PASOE instance.
{CATALINA_BASE}\config\openedge.properties [AppServer.SessMgr]
agentStartLimit=1 Example:
$ pasman oeprop -I oepas1 AppServer.SessMgr.agentStartLimit=1
$ pasman oeprop -I oepas1 AppServer.SessMgr.agentStartLimit
1
