Hi Volker,
Running with ICU should stop harfbuzz use completely so if
you are still seeing a crash, perhaps it is due to something else entirely.
Especially since a "simple AWT program" should not load layout anyway.
There was a fair amount of new and changed code pushed recently ...
Yes, we need to run harfbuzz in multiple concurrent threads in the JDK.
A single threaded lock on harfbuzz would throttle text operations.
I suppose it is possible that we do not strictly need it as we currently
create a
new harfbuzz "instance" each time we go to invoke layout but that
is something that at least theoretically could change.
The approach to synchronization is all from up-stream harfbuzz.
The harfbuzz mailing list might be the place to discuss that.
I'd expect it does work on AIX as a principal driver here is that
the IBM sponsored ICU project has deprecated its layout engine
and IBM/ICU are moving to harfbuzz so I'd be somewhat astonished
if they haven't yet tried it on AIX. Did you try just getting a copy
of the full hotspot library and running its configure on AIX to see if
harfbuzz can work out which options it wants there ? Obviously
I did not try that since I don't have AIX. Steven Loomis of IBM
who submitted the JEP should be able to help with a lot of this.
-phil.
On 12/8/15, 10:50 AM, Volker Simonis wrote:
Hi,
the integration of harfbuzz broke our AIX build because there's no
implementation available for the hb_atomic macros in
hb-atomic-private.hh. I've fixed that locally but still get a crash
when running a simple AWT program (even with
-Dsun.font.layoutengine=icu).
I'm curretnly debugging the problem, but I have some general questions:
1. Do we really need the multi-threaded features of harfbuzz in OpenJDK?
2. Why does hurbuzz require these synchronization macros? From a first
glance it doesn't seem to use multiple threads by itself. Does it have
some global data structures which it needs to protect if harfbuzz is
called from various threads?
3. Is there a way to test the hurfbuzz engine on a new platform? I saw
the new test TestLayoutVsICU.java but it is marked as "manual" and it
seems to require external fonts (at least some of which seem to be
freely available). Could you please provide at least a minimal
description on how this test can be run?
4. Is there a way to test that the implementation of the hb_atomic
macros in hb-atomic-private.hh is correct (i.e. a way to stress
harfbuzz from multiple threads)? I think this is important as I
couldn't find a good description of the requirements for the atomic
macros and on weak memory model architectures we should really get
this right. For example there's no description of which fences are
required around the various atomic operations. Getting this right
across all platforms in the HotSpot (see
hotspot/src/os_cpu/../vm/atomic_os_cp.inline.hpp) is already hard
enough so I'm a little concerned that we are now introducing similar
primitives in the class library.
Thank you and best regards,
Volker
