This is a redo of [JDK-8304824](https://bugs.openjdk.org/browse/JDK-8304824) which was backed out by [JDK-8343726](https://bugs.openjdk.org/browse/JDK-8343726) due to problems documented in [JDK-8343244](https://bugs.openjdk.org/browse/JDK-8343244).
The problem was that `NmtVirtualMemoryLocker` was not locking when the current thread is not attached by checking `Thread::current_or_null_safe() != nullptr`. This is necessary during VM init, but should not be allowed afterward. NMT may be used in `attach_current_thread` before the current thread is set. The lock was not being acquired in that case, which intermittently caused NMT accounting to become corrupted, triggering various assertions when future NMT operations are done. To fix this, I've adopted [Thomas' suggestion](https://github.com/openjdk/jdk/pull/21928#issuecomment-2460238057) to reverse the order of thread->register_thread_stack_with_NMT(); thread->initialize_thread_current(); in `attach_current_thread`. This allows `NmtVirtualMemoryLocker` to be locked after current thread is set. To allow for `NmtVirtualMemoryLocker` to be used during VM init, I've replaced the `ConditionalMutexLocker` check `Thread::current_or_null_safe() != nullptr` with a new flag: `_done_bootstrap`. This flag prevents the lock from being used during VM init, at which point we are single threaded anyway. This avoids errors due to Hotspot mutexes and current thread not yet being ready. I also added new asserts in `virtualMemoryTracker.cpp` to catch future bugs like this where the lock is not held when it should be. I updated the appropriate VMT tests to also lock (there were a few cases where locking was being bypassed) so they can pass the new asserts. I also removed the unused `_query_lock` variable in `MemTracker`. Testing: - On Linux amd64, I was able to consistently reproduce the errors described in [JDK-8343244](https://bugs.openjdk.org/browse/JDK-8343244) by increasing the number of test threads in `java/lang/Thread/jni/AttachCurrentThread/AttachTest.java`. The test consistently passes with the new changes in this PR. - hotspot_nmt , gtest:VirtualSpace, tier1 ------------- Commit messages: - Fix concurrency issue. Add assertions. Update tests. - Revert "8343726: [BACKOUT] NMT should not use ThreadCritical" Changes: https://git.openjdk.org/jdk/pull/22745/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22745&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8346123 Stats: 102 lines in 19 files changed: 54 ins; 24 del; 24 mod Patch: https://git.openjdk.org/jdk/pull/22745.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/22745/head:pull/22745 PR: https://git.openjdk.org/jdk/pull/22745
