Inconsistent execution mode error of example ScanAndSort.cpp

[yizhuoliang]

When I compiled everything in velox on my Linux instance and try to run the example ScanAndSort.cpp, but got aborted due to the "Inconsistent execution mode" issue, where I didn't modify the code

cc@mc-1:~/velox$ ./_build/release/velox/examples/velox_example_scan_and_sort
E20241206 21:21:31.770948 925040 Exceptions.h:66] Line: /home/cc/velox/velox/exec/Task.cpp:787, Function:checkExecutionMode, Expression: mode == mode_ (Serial vs. Parallel) Inconsistent task execution mode., Source: RUNTIME, ErrorCode: INVALID_STATE
terminate called after throwing an instance of 'facebook::velox::VeloxRuntimeError'
  what():  Exception: VeloxRuntimeError
Error Source: RUNTIME
Error Code: INVALID_STATE
Reason: (Serial vs. Parallel) Inconsistent task execution mode.
Retriable: False
Expression: mode == mode_
Function: checkExecutionMode
File: /home/cc/velox/velox/exec/Task.cpp
Line: 787
Stack trace:
# 0  _ZN8facebook5velox7process10StackTraceC1Ei
# 1  _ZN8facebook5velox14VeloxExceptionC1EPKcmS3_St17basic_string_viewIcSt11char_traitsIcEES7_S7_S7_bNS1_4TypeES7_
# 2  _ZN8facebook5velox6detail14veloxCheckFailINS0_17VeloxRuntimeErrorERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEEvRKNS1_18VeloxCheckFailArgsET0_
# 3  _ZN8facebook5velox4exec4Task18checkExecutionModeENS2_13ExecutionModeE
# 4  _ZN8facebook5velox4exec4Task4nextEPN5folly10SemiFutureINS3_4UnitEEE
# 5  main
# 6  0x000000000002a1ca
# 7  __libc_start_main
# 8  _start

*** Aborted at 1733520091 (Unix time, try 'date -d @1733520091') ***
*** Signal 6 (SIGABRT) (0x3e8000e1d70) received by PID 925040 (pthread TID 0x7db799aa51c0) (linux TID 925040) (maybe from PID 925040, UID 1000) (code: -6), stack trace: ***
    @ 0000000002e494b1 _ZN5folly10symbolizer12_GLOBAL__N_113signalHandlerEiP9siginfo_tPv
                       /home/cc/velox/_build/release/_deps/folly-src/folly/experimental/symbolizer/SignalHandler.cpp:453
    @ 000000000004531f (unknown)
    @ 000000000009eb1c pthread_kill
    @ 000000000004526d gsignal
    @ 00000000000288fe abort
    @ 00000000000a5ff4 (unknown)
    @ 00000000000bb0d9 (unknown)
    @ 00000000000a5a54 _ZSt9terminatev
    @ 00000000000bb390 __cxa_throw
    @ 0000000002e04a99 __cxa_throw
                       /home/cc/velox/_build/release/_deps/folly-src/folly/debugging/exception_tracer/ExceptionTracerLib.cpp:159
    @ 0000000002da1a46 _ZN8facebook5velox6detail14veloxCheckFailINS0_17VeloxRuntimeErrorERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEEvRKNS1_18VeloxCheckFailArgsET0_
                       /home/cc/velox/./velox/common/base/Exceptions.h:74
                       -> /home/cc/velox/velox/common/base/Exceptions.cpp
    @ 0000000000f190ae _ZN8facebook5velox4exec4Task18checkExecutionModeENS2_13ExecutionModeE
                       /home/cc/velox/velox/exec/Task.cpp:787
    @ 0000000000f2e233 _ZN8facebook5velox4exec4Task4nextEPN5folly10SemiFutureINS3_4UnitEEE
                       /home/cc/velox/velox/exec/Task.cpp:621
    @ 0000000000c9d0a0 main
                       /home/cc/velox/velox/examples/ScanAndSort.cpp:144
    @ 000000000002a1c9 (unknown)
    @ 000000000002a28a __libc_start_main
    @ 0000000000cbae64 _start
Aborted (core dumped)

I also tried to replace kParallel with kSerial, but this will leads another error says WriterFactory is not registered for format json/dwrf/orc. Any idea on how to make this example actually run? Thank you!

[yizhuoliang]

Well looks like this particular example hasn't been updated for 2 years, thus its APIs are not consistent with current velox implementations. I made some update and now it runs well, considering raising a PR.