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Java 2 SDK for Solaris Developer's Guide

Java HotSpot VM Equivalents of Exact VM Options

For additional information on issues related to the Java HotSpot VM, see the online documentation at http://java.sun.com/j2se/1.4/docs/guide/vm/index.html.

Prior to version 1.3.0, the production releases of the Java 2 SDK for the Solaris Operating Environment shipped with a virtual-machine implementation known as the Exact VM (EVM). Beginning with version 1.3.0, the Exact VM is replaced by the Java HotSpot VM.

Some options supported by the Exact VM have changed names or become obsolete in the Java HotSpot VM. These EVM options and their Java HotSpot VM equivalents in Java 2 SDK v 1.4.0 are given in the following table.

EVM Option 

Description 

Java HotSpot VM equivalent 

-Xt

Instruction tracing 

None (obsolete option) 

-Xtm

Method tracing 

None (obsolete option) 

-Xoss

Maximum java stack size 

None (Java HotSpot VM doesn't have separate native and Java programming language stacks) 

-Xverifyheap

Verify heap integrity 

-XX:+VerifyBeforeGC

-XX:+VerifyAfterGC

-XX:+VerifyTLAB

-XX:+VerifyBeforeScavenge

-XX:+VerifyAfterScavenge (all debug only)

-Xmaxjitcodesize

Maximum compiled code size 

-Xmaxjitcodesize (used to be -Xmaxjitcodesize=32m, now -Xmaxjitcodesize32m)

-Xgenconfig

Configure the heap 

(See The -Xgenconfig Option below.)

-Xoptimize

Use optimizing JIT Compiler 

-server

-Xconcgc

Use concurrent garbage collector (1.2.2_07+) 

None (not yet in 1.3, 1.4) 

The Java HotSpot VM currently recognizes the following -X options that were not supported by the Exact VM.

Option 

Description 

-Xincgc

Use Train GC 

-Xnoincgc

Do not use Train Garbage Collection (default) 

-Xmaxf<Maximum>

Max percentage o fhead free after GC to avoid shrinking (default 0.7) 

-Xminf<Minimum>

Min percentage of heap free after GC to avoid expansion (default 0.4) 

-Xint

Interpreter only 

-Xboundthreads

Bind user-level threads (default in 1.4, not in 1.3) 

-Xmn<Size>

Set the size of the young generation (1.4 only)