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authorjhendersonHDF <jhenderson@hdfgroup.org>2022-01-29 20:22:30 (GMT)
committerGitHub <noreply@github.com>2022-01-29 20:22:30 (GMT)
commit86ef00fd67d4f5007ff8e3390631009ad75891a5 (patch)
tree864ef4983785fd53728c15742c1ddce5b539551e /release_docs/RELEASE.txt
parentbcf95655354ab9c92f823656ee1722fd91694305 (diff)
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Unify handling of collective metadata reads status (#1206)
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@@ -1083,6 +1083,27 @@ Bug Fixes since HDF5-1.12.0 release
(DER - 2021/11/23, HDFFV-11286)
+ - Unified handling of collective metadata reads to correctly fix old bugs
+
+ Due to MPI-related issues occurring in HDF5 from mismanagement of the
+ status of collective metadata reads, they were forced to be disabled
+ during chunked dataset raw data I/O in the HDF5 1.10.5 release. This
+ wouldn't generally have affected application performance because HDF5
+ already disables collective metadata reads during chunk lookup, since
+ it is generally unlikely that the same chunks will be read by all MPI
+ ranks in the I/O operation. However, this was only a partial solution
+ that wasn't granular enough.
+
+ This change now unifies the handling of the file-global flag and the
+ API context-level flag for collective metadata reads in order to
+ simplify querying of the true status of collective metadata reads. Thus,
+ collective metadata reads are once again enabled for chunked dataset
+ raw data I/O, but manually controlled at places where some processing
+ occurs on MPI rank 0 only and would cause issues when collective
+ metadata reads are enabled.
+
+ (JTH - 2021/11/16, HDFFV-10501/HDFFV-10562)
+
- Fixed several potential MPI deadlocks in library failure conditions
In the parallel library, there were several places where MPI rank 0