Database Reference
In-Depth Information
The 32-bit operating system caps the conceptual heap size to around 4 GB. Individu-
al 32-bit operating system's JVM heap size varies anywhere from 2 GB to less than
4 GB. The 64-bit heap size restriction is very high and it can be assumed that it has
no restrictions for currently available server platforms. JVM parameters are a part of
SOA/WebLogic startup scripts or domain environment configurations.
A sample JVM configuration is as follows:
-Xms4096M -Xmx4096M -XX:PermSize=1024M
-XX:MaxPermSize=1024M
JVM troubleshooting tools
Some of the JVM troubleshooting tools are as follows:
•
Logfile messages
: Gather more information from logfiles by adding ad-
ditional troubleshooting parameters as part of the JVM configuration.
• The sample JVM parameters that can be added as part of
the JVM configuration is
-verbose:gc
,
-XX:+PrintGC
,
-XX:+PrintGCDetails,-XX:+PrintGCTimeStamps
,
and
-XX:+HeapDumpOnOutOfMemoryError
•
-XX:+PrintGC
: Provides the basic information at every
garbage collection.
•
-XX:+PrintGCDetails
: Provides the size of live objects
before and after garbage collection for the various genera-
tions, the total available space for each generation and the
length of time the collection took.
