CI/omniscidb/rbc instabilities

[pearu]

The issue is created to log unexplained rbc CI failures.

[pearu]

https://github.com/xnd-project/rbc/runs/5147514875?check_suite_focus=true

rbc/tests/test_omnisci_udtf.py::test_parallel_execution[1-ct_sleep1] TTransportException(type=4, message='TSocket read 0 bytes')
1259
TTransportException(type=4, message='TSocket read 0 bytes')
1260
FAILED

2022-02-10T20:55:16.542814 E 4442 0 2160 DBHandler.cpp:1328 Function ct_device_selection_udf_gpu(INTEGER) not supported.
2022-02-10T20:55:57.065470 E 4442 0 2357 DBHandler.cpp:1328 SQL Error: From line 2, column 12 to line 3, column 53: No match found for function signature dbscan(<CURSOR>, <NUMERIC>, <NUMERIC>, <NUMERIC>)
2022-02-10T20:55:57.070924 E 4442 0 2360 DBHandler.cpp:1328 SQL Error: From line 2, column 12 to line 3, column 35: No match found for function signature kmeans(<CURSOR>, <NUMERIC>, <NUMERIC>)
2022-02-10T20:56:51.126150 E 4442 0 4005 DBHandler.cpp:1328 Error executing table function: TableFunctionManager error_message!
2022-02-10T20:57:05.042444 F 4442 0 52 TableFunctionManager.h:190 Check failed: instance_ == nullptr 

[pearu]

https://github.com/xnd-project/rbc/runs/5148068673?check_suite_focus=true

Same Python failure as above.

2022-02-10T21:49:51.273452 E 4422 0 2160 DBHandler.cpp:1328 Function ct_device_selection_udf_gpu(INTEGER) not supported.
29402
2022-02-10T21:50:22.093218 E 4422 0 2357 DBHandler.cpp:1328 SQL Error: From line 2, column 12 to line 3, column 53: No match found for function signature dbscan(<CURSOR>, <NUMERIC>, <NUMERIC>, <NUMERIC>)
29403
2022-02-10T21:50:22.097723 E 4422 0 2360 DBHandler.cpp:1328 SQL Error: From line 2, column 12 to line 3, column 35: No match found for function signature kmeans(<CURSOR>, <NUMERIC>, <NUMERIC>)
29404
2022-02-10T21:50:46.846521 E 4422 0 3318 File.cpp:304 Failed to remove object data/mapd_data/table_1_12_1644529846845_DELETE_ME error was system:2
29405
2022-02-10T21:51:06.936355 E 4422 0 4005 DBHandler.cpp:1328 Error executing table function: TableFunctionManager error_message!
29406
2022-02-10T21:51:10.834724 F 4422 0 52 TableFunctionManager.h:190 Check failed: instance_ == nullptr 

[pearu]

Running a full set of rbc tests using CPU-only omniscidb shows that pytest consumes about 16GB RAM.