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Fine-grained Control of Metadata Cache Flushes


This document describes some new functions which allow dynamic, fine-grained flush control of the entire metadata cache and the caches related to individual HDF5 objects.
Read Attempts for Metadata with ChecksumThe HDF5 library encounters intermittent checksum failures from reading metadata of an HDF5 file opened with single-writer/multiple-reader (SWMR) access. The failure is from a checksum check that does not reflect the data read. This document describes the modifications to the library that address this problem.
Metadata Cache ImageThis document describes the metadata cache image feature and how it improves performance by writing the metadata cache in a single block on file close, and then populating the cache with the contents of this block on file open. This avoids the many small I/O operations that would otherwise be required on file open and close.
Metadata Cache Evict on CloseThis feature will cause all metadata for an object to be evicted from the cache as long as metadata is not referenced from any other open object. This can relieve memory pressure on an application or system caused by a large amount of metadata in the metadata cache. See the H5P_GET_EVICT_ON_CLOSE and H5P_SET_EVICT_ON_CLOSE APIs for more details.
Metadata Cache LoggingThis document describes the improvements made to the library’s metadata cache logging facility. The changes include APIs that can be used to control logging operations and the format of log messages.
Flush Dependency TestingThis document considers how to design tests for flush dependencies of metadata cache items for single-writer/multiple-reader (SWMR) access.