[OpenJDK 2D-Dev] RFR: 8247872: Upgrade HarfBuzz to the latest 2.7.2
Magnus Ihse Bursie
magnus.ihse.bursie at oracle.com
Tue Nov 17 21:40:33 UTC 2020
On 2020-11-17 19:08, Philip Race wrote:
> So maybe the actual *usage* of C++11 features slows it down.
> I found this :-
> I really did not even think to measure the build time and I don't
> think there's any JDK build parallelism in building a specific native
> The build is parallel at a higher level but not at that lower level.
There is build parallelism on multiple levels. When building an
individual library, make is free to parallelize the compile task; only
the link task is done singlethreaded. When determining which libraries
to build, make is free to chose those available depending on tasks
already finished. For instance, to build java.desktop-libs, we need to
have finished java.desktop-java (since javac generates the header files
needed by JNI integration). But after that, it can be compiled whenever
make think it's suitable.
This freedom for make to reorganize the order also means that it is hard
to determine the additional cost for building a specific part. You could
try to build java.desktop-java, and then run "make LOG=info
java.desktop-libs" JOBS=1 to get a somewhat proper assessment of the
time spent building all native libs for java.desktop. If this changes
with the HarfBuzz upgrade, the HB upgrade is likely to blame.
> On 11/17/20, 10:00 AM, Florian Weimer wrote:
>> * Philip Race:
>>> There is more code in the newer version but not 4 times as much !
>>> Harfbuzz now requires c++11 features (-std=c++11)
>>> Possibly the C++ compiler you are using (you don't mention platform) is
>>> slower in this mode.
>> It's GCC 8 on Debian buster, which defaults to C++14. And it's
>> possible to write slow-to-compile C++ in all language modes.
>> Is the Harfbuzz build parallelized?
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