FYI: probably is better/simpler to review it via webrev.
After migration to the lcms from the kcms the performance of some operations
was regressed. One possible workaround was to split the operation into multiple
threads. But unfortunately, we have too many bottlenecks which prevent using
multithreading. This is the request to remove/minimize such bottlenecks(at
least some of them), but it does not affect the single-threaded performance it
should be handled separately.
The main code pattern optimized here is this:
activate();
byte[] theHeader = getData(cmmProfile, icSigHead);
----> CMSManager.getModule().getTagData(p, tagSignature);
Notes about the code above:
1. Before the change "activate()" method checked that the "cmmProfile" field
was not null. After that we usually used the "cmmProfile" as the parameter to
some other method. This included two volatile reads, and also required to check
when we need to call the "activate()" method before usage of the "cmmProfile"
field.
Solution: "activate()" renamed to the "cmmProfile()" which became an accessor
for the field, so we will get one volatile read and can easily monitor the
usage of the field itself(it is used directly only in this method).
2. The synchronized static method "CMSManager.getModule()" reimplemented to
have only one volatile read.
3. The usage of locking in the "getTagData()" is changed. Instead of the
synchronized instance methods, we now use the mix of "ConcurrentHashMap" and
StampedLock.
See some comments inline.
Some numbers(small numbers are better):
1. Performance of ((ICC_ProfileRGB)
ICC_Profile.getInstance(ColorSpace.CS_sRGB)).getMatrix();
jdk 15.0.2
Benchmark Mode Cnt Score Error Units
CMMPerf.ThreadsMAX.testGetMatrix avgt 5 19,624 ± 0,059 us/op
CMMPerf.testGetMatrix avgt 5 0,154 ± 0,001 us/op
jdk - before the fix
Benchmark Mode Cnt Score Error Units
CMMPerf.ThreadsMAX.testGetMatrix avgt 5 12,935 ± 0,042 us/op
CMMPerf.testGetMatrix avgt 5 0,127 ± 0,007 us/op
jdk - after the fix
Benchmark Mode Cnt Score Error Units
CMMPerf.ThreadsMAX.testGetMatrix avgt 5 0,561 ± 0,005 us/op
CMMPerf.testGetMatrix avgt 5 0,092 ± 0,001 us/op
2. Part of performance gain in jdk17 is from some other fixes, for example
Performance of ICC_Profile.getInstance(ColorSpace.CS_sRGB); and
ColorSpace.getInstance(ColorSpace.CS_sRGB);
jdk 15.0.2
Benchmark Mode Cnt Score Error Units
CMMPerf.ThreadsMAX.testGetSRGBProfile avgt 5 2,299 ± 0,032 us/op
CMMPerf.ThreadsMAX.testGetSRGBSpace avgt 5 2,210 ± 0,051 us/op
CMMPerf.testGetSRGBProfile avgt 5 0,019 ± 0,001 us/op
CMMPerf.testGetSRGBSpace avgt 5 0,018 ± 0,001 us/op
jdk - same before/ after the fix
Benchmark Mode Cnt Score Error Units
CMMPerf.ThreadsMAX.testGetSRGBProfile avgt 5 0,005 ± 0,001 us/op
CMMPerf.ThreadsMAX.testGetSRGBSpace avgt 5 0,005 ± 0,001 us/op
CMMPerf.testGetSRGBProfile avgt 5 0,005 ± 0,001 us/op
CMMPerf.testGetSRGBSpace avgt 5 0,005 ± 0,001 us/op
note "ThreadsMAX" is 32 threads.
-------------
Commit messages:
- Update ICC_Profile.java
- Merge branch 'master' into threads
- Update LCMS.c
- Initial fix
Changes: https://git.openjdk.java.net/jdk/pull/2957/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2957&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8263482
Stats: 212 lines in 5 files changed: 52 ins; 83 del; 77 mod
Patch: https://git.openjdk.java.net/jdk/pull/2957.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/2957/head:pull/2957
PR: https://git.openjdk.java.net/jdk/pull/2957
