On Wed, 28 Aug 2024 03:42:27 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
> ```
> public boolean isSharingEnabled() {
> if (sharingEnabled == null) {
> Address address = VM.getVM().getDebugger().lookup(null,
> "UseSharedSpaces");
> if (address == null && getOS().equals("win32")) {
> // On Win32 symbols are prefixed with the dll name. So look for
> // UseSharedSpaces as a symbol in jvm.dll.
> address = VM.getVM().getDebugger().lookup(null,
> "jvm!UseSharedSpaces");
> }
> sharingEnabled = address.getJBooleanAt(0);
> }
> return sharingEnabled.booleanValue();
> }
> ```
>
> I'm not sure why this is failing. Based on the existing code and comments, it
> seems at some point SA worked without relying on the windbg native symbol
> support. Code like isSharingEnabled() probably got added afterwards and was
> never tested with it disabled.
"UseSharedSpaces" is exported from jvm.dll, but the issue here on Windows
SymbolLookup searches for decorated symbols (i.e. "??_7UseSharedSpaces@@6B@")
and the symbol is exported undecorated.
>From globalDefinition.hpp (note extern "C"):
extern "C" {
// Make sure UseSharedSpaces is accessible to the serviceability agent.
extern JNIEXPORT jboolean UseSharedSpaces;
}
-------------
PR Comment: https://git.openjdk.org/jdk/pull/20684#issuecomment-2316420789
