Hi David, some small changes are needed to make this build and run on AIX. I attached a patch file with the needed additions.
I did not run any extensive tests on AIX, so I cannot say for sure if this is stable. We (SAP) also may face some problems later when we port this to HP-UX, because there, shared libraries using __thread cannot be loaded dynamically. So, I admit to some small worries, beside the issue with memory leaks on older glibc versions. For me, this feels like something which needs tight compiler/thread library support from the OS, so it makes us vulnerable to running on older systems (older glibc) or building with outdated compilers. Therefore it would be nice to have a simple way to re-add the pthread-based TLS implementation if needed. Apart from that, I like the patch and think the simplification is good and worth the effort. Kind Regards, Thomas On Mon, Nov 2, 2015 at 7:40 AM, David Holmes <david.hol...@oracle.com> wrote: > bug: https://bugs.openjdk.java.net/browse/JDK-8132510 > > Open webrev: http://cr.openjdk.java.net/~dholmes/8132510/webrev.v2/ > > A simple (in principle) but wide-ranging change which should appeal to our > Code Deletion Engineer's. We implement Thread::current() using a > compiler/language-based thread-local variable eg: > > > static __thread Thread *_thr_current; > > inline Thread* Thread::current() { > return _thr_current; > } > > with an appropriate setter of course. By doing this we can completely > remove the platform-specific ThreadLocalStorage implementations, and the > associated os::thread_local_storage* calls, plus all the uses of > ThreadLocalStorage::thread() and ThreadLocalStorage::get_thread_slow(). > This extends the previous work done on Solaris to implement > ThreadLocalStorage::thread() using compiler-based thread-locals. > > We can also consolidate nearly all the os_cpu versions of > MacroAssembler::get_thread on x86 into one cpu specific one ( a special > variant is still needed for 32-bit Windows). > > As a result of this change we have further potential cleanups: > - all the src/os/<os>/vm/thread_<os>.inline.hpp files are now completely > empty and could also be removed > - the MINIMIZE_RAM_USAGE define (which avoids use of the linux sp-map > "cache" on 32-bit) now has no affect and so could be completely removed > from the build system > > I plan to do the MINIMIZE_RAM_USAGE removal as a follow up CR, but could > add the removal of the "inline" files to this CR if people think it worth > removing them. > > I have one missing piece on Aarch64 - I need to change > MacroAssembler::get_thread to simply call Thread::current() as on other > platforms, but I don't know how to write that. I would appreciate it if > someone could give me the right code for that. > > I would also appreciate comments/testing by the AIX and PPC64 folk as well. > > A concern about memory-leaks had previously been raised, but experiments > using simple C code on linux 86 and Solaris showed no issues. Also note > that Aarch64 already uses this kind of thread-local. > > Thanks, > David >
aix.patch
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