Diagnosing problems with message logs

WebSphere Application Server can write system messages to several general purpose logs, including JVM, process, and IBM service logs, which can be examined for problem determination.

 

Before you begin

The JVM logs are created by redirecting the System.out and System.err streams of the JVM to independent log files. WAS writes formatted messages to the System.out stream. In addition, applications and other code can write to these streams using the print() and println() methods defined by the streams. Some Developer Kit built-ins such as the printStackTrace() method on the Throwable class can also write to these streams. Typically, the System.out log is used to monitor the health of the running application server. The System.out log can be used for problem determination, but it is recommended to use the IBM Service log and the advanced capabilities of the Log Analyzer instead. The System.err log contains exception stack trace information that is useful when performing problem analysis.

Important: This Log Analyzer tool is different from the Log and Trace Analyzer tool available on the WebSphere® Application Server Toolkit CD-ROM. For information on the WebSphere® Application Server Toolkit Log and Trace Analyzer, refer to the Detecting and analyzing runtime problems documentation provided with the WebSphere® Application Server Toolkit .

Because each application server represents a JVM, there is one set of JVM logs for each application server and all of its applications located by default in the following directory:

In the case of a WebSphere Application Server Network Deployment configuration, JVM logs are also created for the deployment manager and each node agent because they also represent JVMs.

The process logs are created by redirecting the STDOUT and STDERR streams of the process to independent log files. Native code, including the Java virtual machine (JVM) itself, writes to these files. As a general rule, WAS does not write to these files. However, these logs can contain information relating to problems in native code or diagnostic information written by the JVM.

As with JVM logs, there is a set of process logs for each application server, since each JVM is an operating system process. For WebSphere Application Server Network Deployment configuration, a set of process logs is created for the deployment manager and each node agent.

The IBM service log contains both the WebSphere Application Server messages that are written to the System.out stream and some special messages that contain extended service information that is normally not of interest, but can be important when analyzing problems. There is one service log for all WAS JVMs on a node, including all application servers. The IBM Service log is maintained in a binary format and requires a special tool to view. This viewer, the Log Analyzer, provides additional diagnostic capabilities. In addition, the binary format provides capabilities that are utilized by IBM support organizations.

In addition to these general purpose logs, WAS contains other specialized logs that are specific to a particular component or activity. For example, the HTTP server plug-in maintains a special log. Normally, these logs are not of interest, but you might be instructed to examine one or more of these logs while performing specific problem determination procedures. For details on how and when to view the plug-in log, see the Accessing a Web resource through the application server and bypassing the HTTP server subsection of the A Web resource does not display topic.

 

About this task

Sometimes server and application problems can be diagnosed by examining log output from the WebSphere Application Server.

 

Procedure

Determine which type of logs you would like to implement: