Creating JVM

[David Holmes]

Try turning on all logging:

-Xlog:all=trace

and see what it shows.

David
-----

On 3/03/2019 11:24 am, Sparse Way wrote:
> Hello,
> 
> How does the JVM locate and load java base classes during its creation process?
> 
> Since JVM  exits at call_initPhase2(TRAPS) in Threads::create_vm without a stack trace or an exception.
> 
> hotspot/src/share/vm/runtime/thread.cpp:
> 
> ...
> // Phase 2. Module system initialization
> //     This will initialize the module system.  Only java.base classes
> //     can be loaded until phase 2 completes.
> //
> //     Call System.initPhase2 after the compiler initialization and jsr292
> //     classes get initialized because module initialization runs a lot of java
> //     code, that for performance reasons, should be compiled.  Also, this will
> //     enable the startup code to use lambda and other language features in this
> //     phase and onward.
> //
> //     After phase 2, The VM will begin search classes from -Xbootclasspath/a.
> static void call_initPhase2(TRAPS) {
>    TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime));
> 
>    Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
>    instanceKlassHandle klass (THREAD, k);
> 
>    JavaValue result(T_INT);
>    JavaCallArguments args;
>    args.push_int(DisplayVMOutputToStderr);
>    args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
>    JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
>                                           vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
>    if (result.get_jint() != JNI_OK) {
>      vm_exit_during_initialization(); // no message or exception
>    }
> 
>    universe_post_module_init();
> }
> ...
> 
> Specifically when calling java.lang.System.initPhase2(boolean printToStderr, boolean printStackTrace) statically.
> JVM options: "-Djava.home=" + jre,
>                      "--patch-module=" + ext + "java.base=src"
> Replacing --patch-module with -Xbootclasspath/a will not help.
> 
> I am not sure if base classes are loaded in the first place.
> 
> Best regards
>