[JAVA] Leak in JdbcToArrowUtils

[asfimport]

JdbcToArrowUtils::updateVector(VarCharVector, String, boolean, int) does not release the memory that it allocates for the NullableVarCharHolder. This can be verified by changing the first lines of JdbcToArrowTest::testJdbcToArrowValues() to the following:

RootAllocator allocator = new RootAllocator(Integer.MAX_VALUE);
VectorSchemaRoot root = JdbcToArrow.sqlToArrow(conn, table.getQuery(), allocator, Calendar.getInstance());
testDataSets(root);
root.close();
assertEquals(allocator.getAllocatedMemory(), 0);

 

The leak can be fixed by closing the buffer in updateVector. However, I would propose to not use the NullableVarCharHolder in the first place because it creates an unnecessary copy of the string. Instead, I would use BaseVariableWidthVector::setSafe(int index, byte[] value) and BaseVariableWidthVector::setNull(int index) directly.

In addition, I would propose to check for leaks in JdbcToArrowTest.

I am willing to create a patch, so please let me know what approach is preferred.

Reporter: Johannes Luong / @jmaschad

_{Note: This issue was originally created as ARROW-5536. Please see the migration documentation for further details.}

[asfimport]

Todd Farmer / @toddfarmer:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.