Leverage tuning considerations to avoid overload and error
conditions when using the JSR 289 Application Router™ with multiple
applications.
Note: This topic references one or more of the application
server log files. As a recommended alternative, you can configure
the server to use the High Performance Extensible Logging (HPEL) log
and trace infrastructure instead of using SystemOut.log , SystemErr.log, trace.log, and activity.log files on distributed and IBM® i systems. You can also use
HPEL in conjunction with your native z/OS® logging facilities. If you are using HPEL, you can access
all of your log and trace information using the LogViewer command-line
tool from your server profile bin directory. See the information
about using HPEL to troubleshoot applications for more information
on using HPEL.
When you deploy more than one application, you might see the following
errors in the log files when heavy SIP protocol traffic exists for
a single application server or cluster of servers:
- Unexpected and excessive SIP application 503 Server Unavailable
error messages
- Proxy and Server overload errors
Note: These error messages do not occur when you deploy one application.
The proxy server and Session Initiation Protocol (SIP) containers
are not synchronized when they are tracking the amount of messages
that are flowing through the system. Using the application router,
multiple messages might be routed between applications. These messages
cause container message counters to increment even though the messages
do not flow through the proxy server.
You can diagnose this problem when you have the following conditions:
- Heavy SIP protocol traffic exists.
- Multiple applications are deployed on a single node or cluster.
Check the proxy server, the application server SystemOut.log log
files, or both for an unexpected overload condition that is detected
at the proxy server, the application server, or both. Also, look for
503 Server unavailable messages that are logged from the SIP application.
Resolving the problem
Messages are shared
between applications at the SIP container before they are sent to
the proxy server. To avoid these error messages and a decrease in
SIP performance, tune the SIP containers to consider the additional
SIP messages that are generated when using the application router
with multiple applications. Complete the following steps in the administrative
console to tune the SIP containers:
- Expand and click
- Under Container Settings, expand SIP Container Settings and click SIP container.
- Increase the Maximum messages per averaging period value to compensate for the anticipated increase in messages that
are generated by the SIP application router.
- Increase the Maximum application sessions value to compensate for the increased Maximum messages
per averaging period value.
The proxy server cannot detect the amount of messages
that are generated at the server. However, modifications to the following
settings might increase the messaging capacity at the containers for
the number of applications that are deployed per container.
Table 1. DAR and CAR SIP container tuning values. This table lists the DAR and CAR SIP container tuning values
for the number of applications that are deployed per container.
SIP Container |
Single Deployed SIP Application |
Three Deployed SIP Applications |
Maximum messages per averaging period |
value = 26640 |
value = 79920 |
Maximum application sessions |
value = 36000 |
value = 96000 |
Note: The values for the Maximum messages per averaging
period and Maximum application sessions fields depend on the processing power, memory, and the deployed
application. Use the values for these fields as listed in the SIP
container settings topic and adjust them to meet the needs of your
environment.