Vectorization: Thread-safety errors in VectorUDFDate

Caused by: java.lang.NumberFormatException: For input string: ""
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Long.parseLong(Long.java:601)
        at java.lang.Long.parseLong(Long.java:631)
        at java.text.DigitList.getLong(DigitList.java:195)
        at java.text.DecimalFormat.parse(DecimalFormat.java:2051)
        at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1869)
        at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1514)        at java.text.DateFormat.parse(DateFormat.java:364)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.VectorUDFDateString$1.evaluate(VectorUDFDateString.java:48)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.StringUnaryUDF.evaluate(StringUnaryUDF.java:90)        at org.apache.hadoop.hive.ql.exec.vector.expressions.VectorExpression.evaluateChildren(VectorExpression.java:121)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.StringGroupColConcatStringScalar.evaluate(StringGroupColConcatStringScalar.java:50)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.VectorExpression.evaluateChildren(VectorExpression.java:121)
        at org.apache.hadoop.hive.ql.exec.vector.udf.VectorUDFAdaptor.evaluate(VectorUDFAdaptor.java:112)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.VectorExpression.evaluateChildren(VectorExpression.java:121)
        at org.apache.hadoop.hive.ql.exec.vector.expressions.VectorUDFTimestampFieldLong.evaluate(VectorUDFTimestampFieldLong.java:93)
        at org.apache.hadoop.hive.ql.exec.vector.VectorSelectOperator.process(VectorSelectOperator.java:123)
        ... 22 more