Optimizing iterating over a group with 140000 entries

[bmribler]

Part of user's messages from HELP-2606:

...as I am investigating parameters on how to optimize the metadata cache, I discovered the following issue:
When setting the initial MDC size to the maximum allowed value

mdc_config.initial_size = 32*1024*1024;
mdc_config.max_size = 32*1024*1024;
mdc_config.min_size = 1024*1024;

then I got HDF5 errors during file creation:

HDF5-DIAG: Error detected in HDF5 (1.14.4-3) thread 13728:
#000: H5Odeprec.c line 674 in H5Oget_info_by_name2(): can't get deprecated info for object
major: Object header
minor: Can't get value
#001: H5Odeprec.c line 243 in H5O__get_info_old(): can't get data model info for object
major: Object header
minor: Can't get value
#002: H5VLcallback.c line 5992 in H5VL_object_get(): get failed
major: Virtual Object Layer
minor: Can't get value
#003: H5VLcallback.c line 5960 in H5VL__object_get(): get failed
major: Virtual Object Layer
minor: Can't get value
#004: H5VLnative_object.c line 269 in H5VL__native_object_get(): object not found
major: Object header
minor: Object not found
#005: H5Gloc.c line 761 in H5G_loc_info(): can't find object
major: Symbol table
minor: Object not found
#006: H5Gtraverse.c line 824 in H5G_traverse(): internal path traversal failed
major: Symbol table
minor: Object not found
#007: H5Gtraverse.c line 596 in H5G__traverse_real(): traversal operator failed
major: Symbol table
minor: Callback failed
#008: H5Gloc.c line 722 in H5G__loc_info_cb(): can't get object info
major: Symbol table
minor: Can't get value
#009: H5Oint.c line 2071 in H5O_get_info(): unable to load object header
major: Object header
minor: Unable to protect metadata
#010: H5Oint.c line 1028 in H5O_protect(): unable to load object header chunk
major: Object header
minor: Unable to protect metadata
#011: H5AC.c line 1277 in H5AC_protect(): H5C_protect() failed
major: Object cache
minor: Unable to protect metadata
#012: H5Centry.c line 3106 in H5C_protect(): can't load entry
major: Object cache
minor: Unable to load metadata into cache
#013: H5Centry.c line 1179 in H5C__load_entry(): incorrect metadata checksum after all read attempts
major: Object cache
minor: Read failed

This error vanishes when setting the initial MDC size to a smaller value such as mdc_config.initial_size = 1610241024;

Is this a known issue fixed in a more recent version? Would you like me to explore this issue further? At the moment I think I can reproduce it and investigate with other values or code modifications per your recommendations.
....