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Notes on JDK/JRE
3-33
Notes on JDK/JRE
Notes on Java VM
The default JavaVM when using JDK/JRE1.3.1_06 and 1.4.1_01 in Interstage Java Server Package is
Fujitsu JavaVM (FJVM). This default is synonymous with specifying "-fjvm" in the java command option.
Notes on OutOfMemoryError Caused by a Permanent Area
Shortage
The Permanent area is one of heap areas used to manage objects (Java classes and methods) that are
permanently referenced by HostSpotVM (including FJVM), which is a JavaVM introduced to JDK/JRE
1.3 and later. For a Java application that uses many classes and methods, the size of the Permanent
area must be increased. Especially if an OutOfMemroyError occurs irrespective of how much the
maximum heap value (specified in -Xmx) is increased, a Permanent area shortage may be one of the
possible causes. The default size of the Permanent area is as follows:
• JDK1.3.1(HotSpot ClientVM): 32MB
• JDK1.3.1(FJVM, HotSpot ServerVM): 64MB
• JDK1.4.1(HotSpot ClientVM): 64MB
• JDK1.4.1(FJVM, HotSpot ServerVM): 64MB
The size of the Permanent area can be specified using JavaVM option "-XX:MaxPermSize."
Example: Set the maximum size of the Permanent area to 128 MB:
-XX:MaxPermSize=128m
Notes on java.lang.Object.wait()
After JDK/JRE is installed, java.lang.Object.wait() may be released (spurious wakeups) without waiting
for a restart instruction (notification), interruption, or time-out. Therefore, make a program so that wait()
is used in a loop.
Reference: Notes on the return value of java.beans.PropertyDescriptor.getWriteMethod()