When a MID Server connects to an instance, the F5 load balancer picks a node and sends back a cookie, which forces that MID Server to communicate with the same node for the duration of the session. If a node restarts, the MID Server gets a new node, selected at random from the remaining nodes. As time goes on, nodes restarted recently have no clients, while nodes that have been running the longest are connected to the most MID Servers and can experience double the expected load. If the number of waiting API requests from multiple MID Servers on a node exceeds the default database queue limit of 50, the MID Server cannot load credentials, and Discovery stalls. For details, see KB0623705.


Steps to Reproduce


  1. Download and unpack the attached PRB1030759_Workaround.tgz file.
  2. Import the attached script include and probe into the instance.
  3. Run the probe with source = 'get' multiple times.
  4. Notice that the F5 cookie remains the same indefinitely, allowing nodes to accumulate MID Server connections.


  1. Download and unpack the attached PRB1030759_Workaround.tgz file.
    This package contains a javascript probe that clears the most heavily used cookies from each MID Server. This causes the load balancer to randomly select a new node on the next connection, which should smooth the load balancing.
  2. Import each of the xml files in the package into the instance.
    The javascript probe runs a MID Server script include that clears the RemoteGlideRecord cookies. The sensor deletes the output, while the sysauto_script runs the probe against all MID Servers at regular intervals.
  3. The Kingston upgrade contains a fix that clears cookies when an error occurs and on node restart. If you want to discard cookies periodically, edit the sysauto script from the workaround attachment to create a SystemProbe with 'source = clear_cookies'. Otherwise, you should disable or delete the probe, sensor, sysauto script, and the Mid Server script include.

Related Problem: PRB1030759

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Article Information

Last Updated:2019-05-21 11:35:12