Hotspot for BSD / opinion request (original) (raw)

David Holmes david.holmes at oracle.com
Wed Feb 8 02:32:23 UTC 2017

Hi David,

Sorry for the long lag on this. I've been looking into the mutex attribute defaults and it is unfortunate that POSIX allowed PTHREAD_MUTEX_DEFAULT to be an implementation specific alias for one of the other three mutex types: PTHREAD_MUTEX_NORMAL, PTHREAD_MUTEX_ERRORCHECK, PTHREAD_MUTEX_RECURSIVE. But even more unfortunate that FreeBSD decided to map it to ERRORCHECK instead of NORMAL as every other platform seems to do! (I note NetBSD defines a DEFAULT that is compatible with NORMAL, not ERRORCHECK.)

Fixing this for FreeBSD when it is not an officially supported platform is a little messy because we don't want to penalize all the other platforms with extra initialization code. Right now this could be confined to os_bsd.* but this code should be refactored into os_posix.* to be more widely shared.

That aside we do not need to keep an attr object per mutex as they will all share the same attributes. So we would have a single static instance and initialize it once during VM initialization, then use it when creating mutexes. Even then I would structure this so that the use of the attr object is hidden behind a macro so that it is a no-op on platforms that use NORMAL as the default.

I will file a RFE for sharing POSIX-based PlatformEvent/Parker code and include the mutex type issue as part of that.

Thanks, David H.

On 10/01/2017 3:37 AM, David CARLIER wrote:

Hi sure thing

diff --git a/src/os/bsd/vm/osbsd.hpp b/src/os/bsd/vm/osbsd.hpp --- a/src/os/bsd/vm/osbsd.hpp +++ b/src/os/bsd/vm/osbsd.hpp @@ -175,6 +175,7 @@ volatile int Event; volatile int nParked; pthreadmutext mutex[1]; + pthreadmutexattrt attr[1]; pthreadcondt cond[1]; double PostPad[2]; Thread * Assoc; @@ -187,7 +188,11 @@ int status; status = pthreadcondinit(cond, NULL); assertstatus(status == 0, status, "condinit"); - status = pthreadmutexinit(mutex, NULL); + status = pthreadmutexattrinit(attr); + assertstatus(status == 0, status, "attrinit"); + status = pthreadmutexattrsettype(attr, PTHREADMUTEXNORMAL); + assertstatus(status == 0, status, "attrsettype"); + status = pthreadmutexinit(mutex, attr); assertstatus(status == 0, status, "mutexinit"); Event = 0; nParked = 0; @@ -206,6 +211,7 @@ class PlatformParker : public CHeapObj { protected: pthreadmutext mutex[1]; + pthreadmutexattrt attr[1]; pthreadcondt cond[1]; public: // TODO-FIXME: make dtor private @@ -216,7 +222,11 @@ int status; status = pthreadcondinit(cond, NULL); assertstatus(status == 0, status, "condinit"); - status = pthreadmutexinit(mutex, NULL); + status = pthreadmutexattrinit(attr); + assertstatus(status == 0, status, "attrinit"); + status = pthreadmutexattrsettype(attr, PTHREADMUTEXNORMAL); + assertstatus(status == 0, status, "attrsettype"); + status = pthreadmutexinit(mutex, attr); assertstatus(status == 0, status, "mutexinit"); } };

Kind regards. Thanks. On 9 January 2017 at 16:48, Daniel D. Daugherty <daniel.daugherty at oracle.com> wrote: David C., If you sent the patch as an attachment, then you should be advised that the OpenJDK email servers strip attachments. If the patch is relatively small, then you can send it in-line... Dan

On 1/6/17 3:23 PM, David CARLIER wrote: Thanks, here a patch proposal. Kindest regards. On 24 December 2016 at 02:16, David Holmes <david.holmes at oracle.com> wrote: If there is a platform, we support, where the default settings are inappropriate then setting them explicitly would be the right thing to do. David

On 24/12/2016 10:23 AM, Vladimir Kozlov wrote: Hi, Forwarding to mailing lists since I can't answer. May be someone can answer your question on these lists. Regards, Vladimir On 12/23/16 2:17 AM, David CARLIER wrote: Hi, this is my first mail to the maiing list, I have difficulties to push messages to any mailing lists, but as BSD user/dev I was looking at code's part like this one

http://hg.openjdk.java.net/jdk9/dev/hotspot/file/70c6fae64754/src/os/bsd/vm/osbsd.hpp I was wondering if it would be better to explicitally set the attr type to PTHREADMUTEXNORMAL to insure consistency with AIX and Linux (on FreeBSD it is PTHREADMUTEXERRORCHECK by default). What do you think ? Thanks in advance. Kindest regards.

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