Work with message logs

WAS can write system messages to several general purpose logs. These include the JVM logs, the process logs and the IBM service log.

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.

Since each appserver represents a JVM, there is one set of JVM logs for each appserver and all of its applications, located by default in the $WAS_INSTALL/logs/server directory. In the case of a WAS Network Deployment configuration, JVM logs are also created for the deployment manager and each node manager, since 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, WebSphere Application Server 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 appserver, since each JVM is an operating system process, and in the case of a WebSphere Application Server Network Deployment configuration, a set of process logs for the deployment manager and each node manager.

The IBM service log contains both the WAS 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 very specific in nature and are scoped 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 HTTP server and Application Server are working separately, but requests are not passing from HTTP server to Application Server.


See Also

Interpreting the JVM logs
Process logs
Configuring WAS for z/OS variables
Interpreting the service log
Viewing the JVM logs
Configuring the JVM logs
Configuring the service log