HDF5 provides asynchronous APIs for the HDF5 VOL connectors that support asynchronous HDF5 operations using the HDF5 Event Set (H5ES) API. This allows I/O to proceed in the background while the application is performing other tasks.
To support AIO capabilities for the HDF5 VOL connectors, the AIO versions for the functions listed in the table below were added to HDF5 library version 1.13.0 and later. The async version of the function has “
_async” suffix added to the function name. For example, the async version for
H5Fcreate, H5Fflush, H5Fis_accessible, H5Fopen, H5Fclose
H5Gcreate, H5Gget_info, H5Gget_info_by_idx, H5Gget_info_by_name, H5Gclose
H5Dcreate, H5Dopen, H5Dset_extent3, H5Dwrite, H5Dread, H5Dget_space, H5Dclose
H5Acreate, H5Acreate_by_name, H5Aopen, H5Aopen_by_name, H5Aexists, H5Awrite, H5Aread,
H5Lcreate_hard, H5Lcreate_soft, H5delete, H5Ldelete_by_idx, H5Lexists
H5Ocopy, H5Orefresh, H5Oflush, H5Oclose, H5Open, H5Oopen_by_index
H5Ropen_attr, H5Ropen_obj, H5Ropen_region, H5Rdereference
H5Mcreate, H5Mopen, H5Mput, H5Mget, H5Mclose
H5Tcommit, H5Topen, H5Tcopy, H5Tclose
Async versions of the functions have an extra parameter called the event set parameter or
es_id. For example, compare the signatures of
herr_t H5Dclose(hid_t dset_id);
herr_t H5Dclose_async(hid_t dset_id, hid_t es_id);
An event set is an in-memory object that is created by an application and used to track many asynchronous operations with a single object. They function like a ``bag'' -- holding request tokens from one or more asynchronous operations and provide a simple interface for inspecting the status of the entire set of operations.
See the H5ES APIs that were added to the HDF5 library to manage event sets.