Java HotSpot Equivalents of Exact VM Flags
This page is of interest to users of versions of the Java SDK on Solaris older than 1.3.0.
Prior to version 1.3.0, the production releases of the Java 2 SDK for Solaris shipped with a virtual-machine implementation known as the Exact VM (EVM). Beginning with version 1.3.0, the Exact VM was replaced by the Java HotSpot VM.
Java HotSpot VM Equivalents of Exact VM Options
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 are given in the following table.
| EVM Option | Description | Java HotSpot equivalent |
|---|---|---|
| -Xt | Instruction tracing | None (obsolete option) |
| -Xtm | Method tracing | None (obsolete option) |
| -Xoss | Maximum java stack size | None (HotSpot doesn't have separate native and Java stacks) |
| -Xverifyheap | Verify heap integrity |
|
| -Xmaxjitcodesize | Maximum Comiled code size | -Xmaxjitcodesize<num> (used to be -Xmaxjitcodesize=32m, now -Xmaxjitcodesize32m) |
| -Xoptimize | Use optimizing JIT Compiler | -server |
| -Xconcgc | Use concurrent garbage collector (1.2.2_07+) | -XX:+UseConcMarkSweepGC (available beginning with J2SE 1.4.1) |
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) |
| -XX:MaxHeapFreeRatio=<Maximum> | heap free percentage (default 70) |
| -XX:MinHeapFreeRatio=<Minimum> | heap free percentage (default 40) |
| -Xint | Intepreter only (no JIT Compilation) |
| -XX:+UseBoundThreads | Bind user level threads (Solaris only) |
| -Xmn<Size> | Set the size of the young generation (available beginning in J2SE 1.4.0) |
| -XX:+UseParallelGC | Use parallel garbage collection (available beginning in J2SE 1.4.1) |
| -XX:+UseAltSigs | On the Solaris operating environment, the VM uses SIGUSR1 by default, which can sometimes conflict with applications that signal-chain SIGUSR1. -XX:+UseAltSigs will cause the VM to use signals other than SIGUSR1 and SIGUSR2 as the default. Available beginning in J2SE 1.4.1 on the Solaris operating environment. |
Java HotSpot VM Equivalents to _JIT_ARGS Environment Variables Most _JIT_ARGS environment variables are internal debugging options only and have no corresponding Java HotSpot options. Most simply turn off some form of optimization which may have caused instability when first introduced and could be used by the internal testing group to track down problems.
| _JIT_ARGS Environment | HotSpot Option | Description |
|---|---|---|
| jit/jbe | -client/-server | jbe is the same as -Xoptimize in 1.2 based systems, jit is the default. Use -server in 1.3 to replace -Xoptimize (or jbe) in 1.2. |
| trace | -XX:+PrintCompilation | traces methods as compiled |
| V8/V9 | -XX:+UseV8InstrsOnly | Done autmatically on both systems, force architecture using these flags (Sparc/debug only) |
Java HotSpot VM Equivalents _JVM_ARGS Environment Variables
| _JVM_ARGS Environment | HotSpot Option | Description |
|---|---|---|
| bound_threads | -XX:+UseBoundThreads | This option forces all threads to be created as bound threads. |
| fixed_size_young_gen |
| Disable young generation resizing. To do this on HotSpot, simply set the size of the young generation to a constant. |
| gc_stats | -verbose:gc | Turns on various forms of gc statistics gathering. |
| ims_concurrent | none | |
| inline_instrs | -XX:MaxInlineSize=<size> | Integer specifying maximum number of bytecode instructions in a method which gets inlined. |
| -XX:FreqInlineSize=<size> | Integer specifying maximum number of bytecode instructions in a frequently executed method which gets inlined. | |
| inline_print | -XX:+PrintInlining | Print message about inlined methods (debug only) |
| no_parallel_gc | none | |
| sync_final | none | |
| yield_interval | -XX:DontYieldALotInterval=<ms> | (debug only) Interval in milliseconds between yields. |
| monitor_order | none |