Gen 8.6 Comm. Bridge crashes for high number of connections

Products

• Gen
• Gen - Run Time Distributed

Issue/Introduction

After upgrade to Gen 8.6 the Communications Bridge/Comm. Bridge (CB) crashes during a stress test for a large number of connections.

Environment

Release: 8.6
Component: Gen Communications Bridge

Cause

In Gen 8.5 the maximum size of the Common Format Buffer (CFB) used for Gen client/server view data transport was increased from 32 KB to 16 MB and 16 MB became the default memory allocated per Comm. Bridge connection.
For further details, please see "Remove 32 KB CFB Limit" in the Gen 8.5 Release Notes located within the Gen 8.5 doc pdf: https://techdocs.broadcom.com/us/en/ca-mainframe-software/devops/ca-gen/8-5.html 

In Gen 8.6  the default memory allocated per Comm. Bridge connection is also 16 MB.

Resolution

If the large CFB feature is not required to be used Gen 8.5 Comm. Bridge PTFs CCN85001/RO68926 & CCN85003/RO79154 provide a method to set a Windows System environment variable to enable each connection to have the previous lower maximum CFB value of 32 KB. The same method is available in Gen 8.6 GA and later versions.
Set Windows System environment variable VIEWSIZE32K=1 and restart the Comm. Bridge service.

If the large CFB feature is required to be used then either the number of connections per Comm. Bridge server needs to be limited or the available memory needs to be increased.

Additional Information

It has been reported by one user that in very old Gen 8.5 Comm. Bridge tests (probably prior to memory fixes) problems had been encountered with exceeding just 100 connections.
That same user ran a simulation of 150 looping connections/test (echo) transactions through the Gen 8.6 Comm. Bridge to a Gen server and the Comm. Bridge service crashed with iefcbn.exe reporting an exception in file C:\Windows\System32\ucrtbase.dll. The crash was resolved by adding the SYSTEM level environment variable VIEWSIZE32K=1.