On Tue, 4 Feb 2025 01:10:34 GMT, Jiangli Zhou <jian...@openjdk.org> wrote:
> Please review runtime/jni/atExit/TestAtExit.java test change: > > - Remove `BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libatExit := > java.base:libjvm`. Don't explicitly link with libjvm, because it adds > libjvm.so as a recorded dependency to libatExit.so (on Linux for example). > That requires libjvm.so must be resolved and loaded successfully when > libatExit.so is loaded. The static JDK (e.g. static-jdk image) does not > provide a libjvm.so for runtime usage. > - Instead of calling the following functions directly in libatExit.c, change > to look up the functions and calls them using the retrieved function > addresses: > - JNI_GetDefaultJavaVMInitArgs > - JNI_GetCreatedJavaVMs > - JNI_CreateJavaVM > > On Linux (and similar) platform, there is no need to call `dlopen` for libjvm > in libatExit.c explicitly, because the VM must already be loaded by the time > when the libatExit native code is executed. Using `RTLD_DEFAULT` can "find > symbols in the executable and its dependencies, as well as symbols in shared > objects that were dynamically loaded with the RTLD_GLOBAL flag" (see > https://man7.org/linux/man-pages/man3/dlsym.3.html). > https://github.com/openjdk/jdk/blob/9b49597244f898400222cfc252f50a2401ca3e2f/src/java.base/unix/native/libjli/java_md.c#L533 > is where we `dlopen` libjvm with `RTLD_GLOBAL` for unix platform. > > For Windows platform, I added Windows specific code to get the loaded > `jvm.dll` first. If it can't find loaded `jvm.dll`, it then get the handle of > the executable running the current process. The returned handle is used for > finding the function addresses. > > TestAtExit passes with > https://github.com/jianglizhou/jdk/actions/runs/13124407248/job/36619759000. > TestAtExit also pass on static-jdk with my local jtreg run. Also to point it out if it's not clear already, `libjvm.so` is implementation detail. One cannot safely that exists at runtime. The static JDK case is a good example. ------------- PR Comment: https://git.openjdk.org/jdk/pull/23431#issuecomment-2634595988
