[issue18782] sqlite3 row factory and multiprocessing map

[Timothy O'Keefe]

New submission from Timothy O'Keefe:

If you run this code, you will get a segfault. If you a) remove the row factory from the following code or b) use the standard library map() instead of multiprocessing.Pool.map, then the code does not crash.

#!/usr/bin/env python

import sqlite3
import multiprocessing as mp

def main():
    ## --- create a database
    conn = sqlite3.connect(':memory:')
    conn.row_factory = sqlite3.Row
    c = conn.cursor()

    ## --- create example table similar to python docs
    c.execute('''CREATE TABLE stocks (date text, trans text, symbol text, qty real, price real)''')
    c.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','GOOG',100,869.29)")
    c.execute("INSERT INTO stocks VALUES ('1992-01-06','SELL','AAPL',20,512.99)")
    c.execute("SELECT * FROM stocks")

    ## --- map fun over cursor iterable (fun does nothing)
    pool = mp.Pool(processes=mp.cpu_count())
    features = pool.map(fun, c)

def fun(row):
    return row

if __name__ == "__main__":
    main()

----------
messages: 195641
nosy: tokeefe
priority: normal
severity: normal
status: open
title: sqlite3 row factory and multiprocessing map
type: crash
versions: Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18782>
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