Failing tests with HDF5 API tests for VOLS.

[brtnfld]

For the serial tests (test/API in HDF5), only h5_api_test_attribute fails with:

1: Testing shared datatype for attributes                                *FAILED*
1:     reference count of the named datatype is wrong: 1

For the parallel tests (testpar/API), only h5_api_test_parallel_async fails with:

9: **********************************************
9: *                                            *
9: *      API Parallel Async Tests              *
9: *                                            *
9: **********************************************
9: 
9: Testing single dataset I/O                         
9:   Testing test setup                                                  HDF5-DIAG: Error detected in HDF5 (1.15.0) MPI-process 0:
9:   #000: ../../src/H5VLcallback.c line 6321 in H5VLintrospect_get_conn_cls(): NULL obj pointer
9:     major: Invalid arguments to routine
9:     minor: Bad value
9: HDF5-DIAG: Error detected in HDF5 (1.15.0) MPI-process 0:
9:   #000: ../../src/H5VL.c line 658 in H5VLobject_is_native(): can't determine if object is a native connector object
9:     major: Virtual Object Layer
9:     minor: Can't get value
9:   #001: ../../src/H5VLint.c line 1077 in H5VL_object_is_native(): can't get VOL connector class
9:     major: Virtual Object Layer
9:     minor: Can't get value
9:   #002: ../../src/H5VLcallback.c line 6289 in H5VL_introspect_get_conn_cls(): can't query connector class
9:     major: Virtual Object Layer
9:     minor: Can't get value
9:   #003: ../../src/H5VLcallback.c line 6256 in H5VL__introspect_get_conn_cls(): can't query connector class
9:     major: Virtual Object Layer
9:     minor: Can't get value
9:   #004: ../../src/H5VLcallback.c line 6321 in H5VLintrospect_get_conn_cls(): NULL obj pointer
9:     major: Invalid arguments to routine
9:     minor: Bad value
9: *FAILED*

[houjun]

@brtnfld, for the failed serial test, I cannot find the root cause of how the reference count is wrong, can we skip this test when testing async vol for now?
I'm looking into the parallel test issue.

[brtnfld]

We should be able to skip the serial test for now. Were you able to reproduce the failures?
Thanks for looking into this.

[houjun]

Yes, I can reproduce the error with the parallel test, the error is due to the file object not being created (because of async) when H5VL_object_is_native is called, thus leading to the NULL obj pointer error. I will work on a fix.