Operating Systems: i5/OS
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JVM log interpretation
View the JVM log files to determine problems within application
environments.
The JVM logs contain print data written by applications. The application
can write this data directly in the form of System.out.print(), System.err.print(),
or other method calls. The application can also write data indirectly by calling
a JVM function, such as an Exception.printStackTrace(). In addition,
the System.out JVM log contains system messages written by the WebSphere
Application Server.
You can format application data to look like WebSphere
Application Server system messages by using the Installed Application Output
field of the JVM Logs properties
panel, or as plain text with no additional formatting. WebSphere Application
Server system messages are always formatted. Depending on how the JVM log
is configured, formatted messages can be written to the JVM logs in either
basic or advanced format.
Message formats
Formatted
messages are written to the JVM logs in one of two formats:
- Basic Format
-
The format used in earlier versions of WebSphere Application Server.
- Advanced Format
-
Extends the basic format by adding information about an event, when possible.
Basic and advanced format fields
Basic
and Advanced Formats use many of the same fields and formatting techniques.
The various fields that may be found in these formats follow:
- TimeStamp
-
The timestamp is formatted using the locale of the process where it is
formatted. It includes a fully qualified date (for example YYMMDD), 24 hour
time with millisecond precision and a time zone.
- ThreadId
-
An 8 character hexadecimal value generated from the hash code of the thread
that issued the message.
- ThreadName
-
The name of the Java thread that issued the message or trace event.
- ShortName
-
The abbreviated name of the logging component that issued the message
or trace event. This is typically the class name for WebSphere Application
Server internal components, but can be some other identifier for user applications.
- LongName
-
The full name of the logging component that issued the message or trace
event. This is typically the fully qualified class name for WebSphere Application
Server internal components, but can be some other identifier for user applications.
- EventType
-
A one character field that indicates the type of the message or trace
event. Message types are in upper case. Possible values include:
- F
-
A Fatal message.
- E
-
An Error message.
- W
-
A Warning message.
- A
-
An Audit message.
- I
-
An Informational message.
- C
-
An Configuration message.
- D
-
A Detail message.
- O
-
A message that was written directly to System.out by the user
application or internal components.
- R
-
A message that was written directly to System.err by the user
application or internal components.
- Z
-
A placeholder to indicate the type was not recognized.
- ClassName
-
The class that issued the message or trace event.
- MethodName
-
The method that issued the message or trace event.
- Organization
-
The organization that owns the application that issued the message or
trace event.
- Product
-
The product that issued the message or trace event.
- Component
-
The component within the product that issued the message or trace event.
Basic format
Message events
displayed in basic format use the following format. The notation <name>
indicates mandatory fields that will always appear in the basic format message.
The notation [name] indicates optional or conditional fields that will be
included if they can be determined.
<timestamp><threadId><shortName><eventType>[className][methodName]<message>
Advanced format
Message
events displayed in advanced format use the following format. The notation <name>
is used to indicate mandatory fields that will always appear in the advanced
format for message entries. The notation [name] is used to indicate optional
or conditional fields that will be included if they can be determined.
<timestamp><threadId><eventType><UOW><source=longName>[className]
[methodName]<Organization><Product><Component>
[thread=threadName]<message>
Related tasks
Configuring the JVM logs
Viewing JVM logs
Reference topic