Is setting -Dsun.jnu.encoding from the command line supposed to work?

[Volker Simonis]

Hi,

is setting -Dsun.jnu.encoding from the command line supposed to work
(i.e. if it should have any impact)?

I'm just asking, because currently it doesn't make any difference.
While the command line arguments get parsed very early during VM
startup in Arguments::parse_each_vm_init_arg() they are only added to
the actual list of system properties later when
Java_java_lang_System_initProperties() (at System.c:398) calls
JVM_InitProperties():

Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xe50cfc]  set_property(Handle, char const*, char
const*, Thread*)+0x30
V  [libjvm.so+0xe510ec]  JVM_InitProperties+0xff4cd404
C  [libjava.so+0x25860]
Java_java_lang_System_initProperties+0xfffc3d50 (System.c:398)
j  java.lang.System.initProperties(Ljava/util/Properties;)Ljava/util/Properties;+0
j  java.lang.System.initializeSystemClass()V+13
v  ~StubRoutines::call_stub
V  [libjvm.so+0xdbc940]  JavaCalls::call_helper(JavaValue*,
methodHandle const&, JavaCallArguments*, Thread*)+0x628
V  [libjvm.so+0x11500d0]  os::os_exception_wrapper(void
(*)(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*),
JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x68
V  [libjvm.so+0xdbc2d0]  JavaCalls::call(JavaValue*, methodHandle
const&, JavaCallArguments*, Thread*)+0xb4
V  [libjvm.so+0xdbbef0]  JavaCalls::call_static(JavaValue*,
KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x13c
V  [libjvm.so+0xdbc010]  JavaCalls::call_static(JavaValue*,
KlassHandle, Symbol*, Symbol*, Thread*)+0x7c
V  [libjvm.so+0x135be0c]  call_initializeSystemClass(Thread*)+0xd0
V  [libjvm.so+0x13656a4]
Threads::initialize_java_lang_classes(JavaThread*, Thread*)+0x294
V  [libjvm.so+0x1365ff4]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x630
V  [libjvm.so+0xe15674]  JNI_CreateJavaVM_inner(JavaVM_**, void**, void*)+0x100
V  [libjvm.so+0xe15954]  JNI_CreateJavaVM+0xff493a9c
C  [libjli.so+0x108e4]  InitializeJVM+0x1b4
C  [libjli.so+0xda54]  JavaMain+0xcc

Unfortunately that's a little too late, because the "sun.jnu.encoding"
property is already set just at the beginning of
Java_java_lang_System_initProperties() (in System.c:189) by calling
GetJavaProperties() which in turn sets the property to the value
detected by ParseLocale(). This finally is either the result of
setlocale(LC_CTYPE, NULL) on Unix or "UTF-8 on MacOS X.

C  [libjava.so+0x2d734]  ParseLocale+0x34
C  [libjava.so+0x2e070]  GetJavaProperties+0x220
C  [libjava.so+0x211d8]
Java_java_lang_System_initProperties+0xfffbf6c8 (System.c:189)
j  java.lang.System.initProperties(Ljava/util/Properties;)Ljava/util/Properties;+0
j  java.lang.System.initializeSystemClass()V+13
v  ~StubRoutines::call_stub
V  [libjvm.so+0xdbc940]  JavaCalls::call_helper(JavaValue*,
methodHandle const&, JavaCallArguments*, Thread*)+0x628
V  [libjvm.so+0x11500d0]  os::os_exception_wrapper(void
(*)(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*),
JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x68
V  [libjvm.so+0xdbc2d0]  JavaCalls::call(JavaValue*, methodHandle
const&, JavaCallArguments*, Thread*)+0xb4
V  [libjvm.so+0xdbbef0]  JavaCalls::call_static(JavaValue*,
KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x13c
V  [libjvm.so+0xdbc010]  JavaCalls::call_static(JavaValue*,
KlassHandle, Symbol*, Symbol*, Thread*)+0x7c
V  [libjvm.so+0x135be0c]  call_initializeSystemClass(Thread*)+0xd0
V  [libjvm.so+0x13656a4]
Threads::initialize_java_lang_classes(JavaThread*, Thread*)+0x294
V  [libjvm.so+0x1365ff4]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x630
V  [libjvm.so+0xe15674]  JNI_CreateJavaVM_inner(JavaVM_**, void**, void*)+0x100
V  [libjvm.so+0xe15954]  JNI_CreateJavaVM+0xff493a9c
C  [libjli.so+0x108e4]  InitializeJVM+0x1b4
C  [libjli.so+0xda54]  JavaMain+0xcc

But between the calls to GetJavaProperties() and JVM_InitProperties()
the jdk already initializes the platform encoding ('fastEncoding' or
'jnuEncoding' in jni_util.c) when it first calls
JNU_NewStringPlatform():

#0  initializeEncoding () at jni_util.c:626
#1  JNU_NewStringPlatform () at jni_util.c:727
#2  GetStringPlatform () at java_props_md.c:601
#3  Java_java_lang_System_initProperties () at System.c:371

There it evaluates the value of the "sun.jnu.encoding" property (which
was taken from the the result of setlocale(LC_CTYPE, NULL) in
ParseLocale()). These values aren't changed any more after the value
of "sun.jnu.encoding" will be changed trough the call of
JVM_InitProperties() to the value set from the command line.

Is this the way how it is supposed to work?

I personally think it would be useful to be able to change
"sun.jnu.encoding" from the command line (even if this would be only
used for testing). But that would probably mean that we would have to
already handle -Dsun.jnu.encoding specially in the launcher. What do
you think?

Regards,
Volker