Fatal Python error: GC object already tracked

[simkoc]

When using the library by running up and down the parse tree and extracting used columns and attributes of the parsed query I frequently ran into inexplicable errors and eventually into segmentation faults that crashed my python program. When going for a proof of concept I ended with the following code that only works for me with iPython. However, I am pretty sure that the problem is not iPython but sqlparser as segmentation faults occurred on multiple occasions when using the library and when doing the proof of concept I was able to eliminate everything but sqlparser related code - however the overall error changed to the GC problem.

I am using:

• an Ubuntu 14.04
• Python 2.7.6 (default, Oct 26 2016, 20:30:19)
• IPython 1.2.1

The code:

import sqlparser

def analyze_result_column_list(node):
    ret = []
    for subnode in node.list:
        if subnode.expr.leftOperand is not None:
            operand = subnode.expr.leftOperand
            for item in operand.caseExpression.whenClauseItemList:
                ret.append(item.comparison_expr.leftOperand.objectOperand.get_text())
    return ret


def analyze_select_statement(root):
    result_attributes = analyze_result_column_list(root.resultColumnList)
    return [], []


class SqlQuery():
    _query_string = None
    _defines = None
    _uses = None

    def __init__(self, stmt, vendor=sqlparser.gsp_dbvendor.dbvmysql):
        root = stmt.get_root()
        self._uses, self._defines = analyze_select_statement(root)


parser = sqlparser.Parser()
query = "SELECT (CASE WHEN password = MD5( 'bitnami ') THEN 1 ELSE 0 END) AS zend_auth_credential_match FROM si_user WHERE (email = 'user@example.com ')"
parser.check_syntax(query)
stmt = parser.get_statement(0)
pq = SqlQuery(stmt)
pq._defines
pq._uses
print "This was a triump,h \nI make a note here: \nHUGE SUCCESS."

Removing self._uses, self._defines = analyze_select_statement(root) leads to the error not manifesting.

The bug can be recreated using a fresh virtual environment and then installing nothing but the sqlparser ,as described in the readme. Then do the following steps:

1. activate the virtenv
2. start IPython
3. mark and copy the above code
4. type %paste

Python 2.7.6 (default, Oct 26 2016, 20:30:19) 
Type "copyright", "credits" or "license" for more information.

IPython 1.2.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: %paste
import sqlparser

def analyze_result_column_list(node):
    ret = []
    for subnode in node.list:
        if subnode.expr.leftOperand is not None:
            operand = subnode.expr.leftOperand
            for item in operand.caseExpression.whenClauseItemList:
                ret.append(item.comparison_expr.leftOperand.objectOperand.get_text())
    return ret


def analyze_select_statement(root):
    result_attributes = analyze_result_column_list(root.resultColumnList)
    return [], []


class SqlQuery():
    _query_string = None
    _defines = None
    _uses = None

    def __init__(self, stmt, vendor=sqlparser.gsp_dbvendor.dbvmysql):
        root = stmt.get_root()
        self._uses, self._defines = analyze_select_statement(root)


parser = sqlparser.Parser()
query = "SELECT (CASE WHEN password = MD5( 'bitnami ') THEN 1 ELSE 0 END) AS zend_auth_credential_match FROM si_user WHERE (email = 'user@example.com ')"
parser.check_syntax(query)
stmt = parser.get_statement(0)
pq = SqlQuery(stmt)
pq._defines
pq._uses

## -- End pasted text --
Fatal Python error: GC object already tracked
Aborted (core dumped)

If any additional feedback/versions/etc. are needed please notify me as I am happy to help in any way possible to get to the root of this issue.