On Fri, 1 Dec 2023 11:33:46 GMT, Joachim Kern <jk...@openjdk.org> wrote:
> On AIX, repeated calls to dlopen referring to the same shared library may > result in different, unique dl handles to be returned from libc. In that it > differs from typical libc implementations that cache dl handles. > > This causes problems in the JVM with code that assumes equality of handles. > One such problem is in the JVMTI agent handler. That problem was fixed with a > local fix to said handler > ([JDK-8315706](https://bugs.openjdk.org/browse/JDK-8315706)). However, this > fix causes follow-up problems since it assumes that the file name passed to > `os::dll_load()` is the file that has been opened. It prevents efficient, > os_aix.cpp-local workarounds for other AIX issues like the *.so/*.a duality. > See [JDK-8320005](https://bugs.openjdk.org/browse/JDK-8320005). As such, it > is a hack that causes other, more uglier hacks to follow (see discussion of > https://github.com/openjdk/jdk/pull/16604). > > We propose a different, cleaner way of handling this: > > - Handle this entirely inside the AIX versions of os::dll_load and > os::dll_unload. > - Cache dl handles; repeated opening of a library should return the cached > handle. > - Increase handle-local ref counter on open, Decrease it on close > - Make sure calls to os::dll_load are matched to os::dll_unload (See > [JDK-8320830](https://bugs.openjdk.org/browse/JDK-8320830)). > > This way we mimic dl handle equality as it is implemented on other platforms, > and this works for all callers of os::dll_load. This pull request has now been integrated. Changeset: b8ae4a8c Author: Joachim Kern <jk...@openjdk.org> Committer: Martin Doerr <mdo...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/b8ae4a8c0985d1763ac48ba78943d8b992d7be77 Stats: 446 lines in 12 files changed: 332 ins; 108 del; 6 mod 8320890: [AIX] Find a better way to mimic dl handle equality Reviewed-by: stuefe, mdoerr ------------- PR: https://git.openjdk.org/jdk/pull/16920
