[C++] Valgrind failure in Grouper.BooleanKey (uninitialized values)

[asfimport]

From the nightlies.

[ RUN      ] Grouper.BooleanKey
==11849== Conditional jump or move depends on uninitialised value(s)
==11849==    at 0x4122555: arrow::TestInitialized(arrow::ArrayData const&) (gtest_util.cc:675)
==11849==    by 0x431604: arrow::compute::(anonymous namespace)::ValidateOutput(arrow::ArrayData const&) (test_util.cc:202)
==11849==    by 0x431F94: arrow::compute::ValidateOutput(arrow::Datum const&) (test_util.cc:235)
==11849==    by 0x40010B: arrow::compute::TestGrouper::ValidateConsume(arrow::compute::ExecBatch const&, arrow::Datum const&) (hash_aggregate_test.cc:380)
==11849==    by 0x400C03: arrow::compute::TestGrouper::ConsumeAndValidate(arrow::compute::ExecBatch const&, arrow::Datum*) (hash_aggregate_test.cc:364)
==11849==    by 0x410BD5: ExpectConsume (hash_aggregate_test.cc:318)
==11849==    by 0x410BD5: arrow::compute::TestGrouper::ExpectConsume(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (hash_aggregate_test.cc:307)
==11849==    by 0x410F74: arrow::compute::Grouper_BooleanKey_Test::TestBody() (hash_aggregate_test.cc:415)
==11849==    by 0x5D7398D: void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x5D73BE0: testing::Test::Run() (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x5D73F0E: testing::TestInfo::Run() (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x5D74035: testing::TestSuite::Run() (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x5D745EB: testing::internal::UnitTestImpl::RunAllTests() (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x5D74858: testing::UnitTest::Run() (in /opt/conda/envs/arrow/lib/libgtest.so)
==11849==    by 0x421207E: main (in /opt/conda/envs/arrow/lib/libgtest_main.so)
==11849== 
{
   <insert_a_suppression_name_here>
   Memcheck:Cond
   fun:_ZN5arrow15TestInitializedERKNS_9ArrayDataE
   fun:_ZN5arrow7compute12_GLOBAL__N_114ValidateOutputERKNS_9ArrayDataE
   fun:_ZN5arrow7compute14ValidateOutputERKNS_5DatumE
   fun:_ZN5arrow7compute11TestGrouper15ValidateConsumeERKNS0_9ExecBatchERKNS_5DatumE
   fun:_ZN5arrow7compute11TestGrouper18ConsumeAndValidateERKNS0_9ExecBatchEPNS_5DatumE
   fun:ExpectConsume
   fun:_ZN5arrow7compute11TestGrouper13ExpectConsumeERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES9_
   fun:_ZN5arrow7compute23Grouper_BooleanKey_Test8TestBodyEv
   fun:_ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc
   fun:_ZN7testing4Test3RunEv
   fun:_ZN7testing8TestInfo3RunEv
   fun:_ZN7testing9TestSuite3RunEv
   fun:_ZN7testing8internal12UnitTestImpl11RunAllTestsEv
   fun:_ZN7testing8UnitTest3RunEv
   fun:main
} 

Reporter: David Li / @lidavidm
Assignee: David Li / @lidavidm

PRs and other links:

• GitHub Pull Request #11041

_{Note: This issue was originally created as ARROW-13812. Please see the migration documentation for further details.}

[asfimport]

David Li / @lidavidm:
So what's going on here took me a while to unwind, but:

• We're generating the array of unique values for a bool.

• Ultimately this happens in BitUtil::bytes_to_bits. This reads 8 bytes and packs them into one byte.

• The buffer it reads is generated by EncoderInteger::Decode. This writes data into a buffer given to it.

• The buffer given to it ultimately stems from a TempVectorStack, whose memory is not initialized.

  And in this test case, we're generating an array of 3 bools. So from Valgrind's perspective, we're taking 3 bytes and 5 garbage bytes and packing it into one garbage byte. I think the solution should be to always round up to 8 bytes.

[asfimport]

Yibo Cai / @cyb70289:
Issue resolved by pull request 11041
#11041