What is Unlock Diagnostic VM Options: -XX:+UnlockDiagnosticVMOptions?

Usage:
• -XX:+UnlockDiagnosticVMOptions

Description:

The -XX:+UnlockDiagnosticVMOptions flag unlocks additional options for diagnosing faults or performance problems with the JVM.
The flags that require unlocking with -XX:+UnlockDiagnosticVMOptions are
as follows:

• -XX:CompilerDirectivesFile
• -XX:+CompilerDirectivesPrint
• -XX:+LogCompilation
• -XX:+PrintAssembly
• -XX:+PrintInlining
• -XX:+UseAES
• -XX:+UseAESIntrinsics
• -XX:+UseAESCTRIntrinsics
• -XX:+UseGHASHIntrinsics
• -XX:+UseBASE64Intrinsics
• -XX:+UseAdler32Intrinsics
• -XX:+UseCRC32Intrinsics
• -XX:+UseCRC32CIntrinsics
• -XX:+UseSHA
• -XX:+UseSHA1Intrinsics
• -XX:+UseSHA256Intrinsics
• -XX:+UseSHA512Intrinsics
• -XX:+UseMathExactIntrinsics
• -XX:+UseMultiplyToLenIntrinsic
• -XX:+UseSquareToLenIntrinsic
• -XX:+UseMulAddIntrinsic
• -XX:+UseMontgomeryMultiplyIntrinsic
• -XX:+UseMontgomerySquareIntrinsic

These flags should not be enabled as a matter of course in a production system,
but should only by used when attempting to diagnose a bug or performance issue.

Default Value:

-XX:+UnlockDiagnosticVMOptions is off by default, i..e the diagnostic options
are not unavailable.

Errors:

Example of using a flag that requires -XX:+UnlockDiagnosticVMOptions but
without supplying that flag:

java -XX:+CompilerDirectivesPrint

The output of the above command is:

Error: VM option 'CompilerDirectivesPrint' is diagnostic and must
be enabled via -XX:+UnlockDiagnosticVMOptions.
Error: The unlock option must precede 'CompilerDirectivesPrint'.
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

Arguments Related to -XX:+UnlockDiagnosticVMOptions

TODO: link to all of the following flags:

• -XX:CompilerDirectivesFile-
• -XX:+CompilerDirectivesPrint
• -XX:+LogCompilation
• -XX:+PrintAssembly
• -XX:+PrintInlining
• -XX:+UseAES
• -XX:+UseAESIntrinsics
• -XX:+UseAESCTRIntrinsics
• -XX:+UseGHASHIntrinsics
• -XX:+UseBASE64Intrinsics
• -XX:+UseAdler32Intrinsics
• -XX:+UseCRC32Intrinsics
• -XX:+UseCRC32CIntrinsics
• -XX:+UseSHA
• -XX:+UseSHA1Intrinsics
• -XX:+UseSHA256Intrinsics
• -XX:+UseSHA512Intrinsics
• -XX:+UseMathExactIntrinsics
• -XX:+UseMultiplyToLenIntrinsic
• -XX:+UseSquareToLenIntrinsic
• -XX:+UseMulAddIntrinsic
• -XX:+UseMontgomeryMultiplyIntrinsic
• -XX:+UseMontgomerySquareIntrinsic

Related Posts:

None

NOTE:

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