需求：

小程序后台用的sqllite数据库，刚开始用的时候，没有考虑多线程，而且当时因为数据量少，没有出现过多线程查询报错，现在数据量大了。多线程查询经常报错

ProgrammingError: Recursive use of cursors not allowed.

就是这个头疼的错。在网上查了大量的资料，要么就是加lock=threading.lock(),要么就是加sleep.终究还是解决不了问题。
刚好最近在网上看了一个小哥哥用Queue来解决这个问题。我改进了一下。目前能够使用该方法进行增删改查。查询出来的结果以字典的形式返回。
话不多说，下面上代码

代码

# -*- coding: UTF-8 -*-
import sqlite3
import time
from Queue import Queue
from threading import Thread
def sqllite_escape(key_word):
    key_word = key_word.encode("utf-8")
    key_word = key_word.replace("'", "''")
    return key_word
class SelectConnect(object):
    '''
    只能用来查询
    '''
    def __init__(self):
        # isolation_level=None为智能提交模式，不需要commit
        self.conn = sqlite3.connect('resource/data.ta', check_same_thread=False, isolation_level=None)
        self.conn.execute('PRAGMA journal_mode = WAL')
        cursor = self.conn.cursor()
        cursor.execute('PRAGMA synchronous=OFF')
        self.conn.text_factory = str
        # 把结果用元祖的形式取出来
        self.curosr = self.conn.cursor()
        self.conn.row_factory = self.dict_factory
        # 把结果用字典的形式取出来
        self.curosr_diction = self.conn.cursor()
    def commit(self):
        self.conn.commit()
    def dict_factory(self, cursor, row):
        d = {}
        for idx, col in enumerate(cursor.description):
            d[col[0]] = row[idx]
        return d
    def close_db(self):
        # self.curosr.close()
        self.conn.close()
class SqliteMultithread(Thread):
    """
    Wrap sqlite connection in a way that allows concurrent requests from multiple threads.
    This is done by internally queueing the requests and processing them sequentially
    in a separate thread (in the same order they arrived).
    """
    def __init__(self, filename, autocommit, journal_mode):
        super(SqliteMultithread, self).__init__()
        self.filename = filename
        self.autocommit = autocommit
        self.journal_mode = journal_mode
        self.reqs = Queue()  # use request queue of unlimited size
        self.setDaemon(True)  # python2.5-compatible
        self.running = True
        self.start()
    def dict_factory(self, cursor, row):
        # field = [i[0] for i in cursor.description]
        # value = [dict(zip(field, i)) for i in records]
        d = {}
        for idx, col in enumerate(cursor.description):
            d[col[0]] = row[idx]
        return d
    def run(self):
        if self.autocommit:
            conn = sqlite3.connect(self.filename, isolation_level=None, check_same_thread=False)
        else:
            conn = sqlite3.connect(self.filename, check_same_thread=False)
        conn.execute('PRAGMA journal_mode = %s' % self.journal_mode)
        conn.text_factory = str
        cursor = conn.cursor()
        cursor.execute('PRAGMA synchronous=OFF')
        conn.row_factory = self.dict_factory
        curosr_diction = conn.cursor()
        curosr_diction.execute('PRAGMA synchronous=OFF')
        # 把结果用字典的形式取出来
        while self.running:
            req, arg, res = self.reqs.get()
            if req == '--close--':
                break
            elif req == '--commit--':
                conn.commit()
            else:
                # print(arg)
                curosr_diction.execute(req, arg)
                # if res:
                #     for rec in cursor:
                #         res.put(rec)
                #     res.put('--no more--')
                if res:
                    res.put(curosr_diction.fetchall())
                if self.autocommit:
                    conn.commit()
        conn.close()
    def execute(self, req, arg=None, res=None):
        """
        `execute` calls are non-blocking: just queue up the request and return immediately.
        """
        self.reqs.put((req, arg or tuple(), res))
    def executemany(self, req, items):
        for item in items:
            self.execute(req, item)
    def select_all_dict(self, req, arg=None):
        '''
        直接返回一个list
        :param req:
        :param arg:
        :return:
        '''
        res = Queue()  # results of the select will appear as items in this queue
        self.execute(req, arg, res)
        rec = res.get()
        return rec
    def select_one_dict(self, req, arg=None):
        '''
        直接返回list里的第一个元素，并且以字典展示
        :param req:
        :param arg:
        :return:
        '''
        res = Queue()  # results of the select will appear as items in this queue
        self.execute(req, arg, res)
        rec = res.get()
        if len(rec) != 0:
            rec = rec[0]
        else:
            rec = None
        return rec
    def commit(self):
        self.execute('--commit--')
    def close(self):
        self.execute('--close--')
class Cursor(object):
    '''
    以元祖的形式查询出数据
    '''
    def __init__(self):
        old_con = SelectConnect()
        self.conn = old_con.conn
        self.curosr = old_con.curosr
        self.curosr2 = SqliteMultithread('resource/data.ta', autocommit=True, journal_mode="WAL")
    def execute(self, string, *args):
        try:
            if string.startswith('select'):
                return self.curosr.execute(string, *args)
            else:
                return self.curosr2.execute(string, *args)
        except Exception:
            print("失败一次")
            print(string)
            time.sleep(0.1)
            self.execute(string, *args)
    def executescript(self, string):
        try:
            self.curosr.executescript(string)
        except Exception:
            print("失败一次")
            print(string)
            time.sleep(0.1)
            self.executescript(string)
    def fetchall(self):
        return self.curosr.fetchall()
    def fetchone(self):
        return self.curosr.fetchone()
    def rowcount(self):
        return self.curosr.rowcount
    def close(self):
        self.curosr2.running = False
        self.curosr.close()
        self.conn.close()
class Curosrdiction(object):
    '''
    以字典的形式查询出数据，建议全部用这种。
    '''
    def __init__(self):
        old_con = SelectConnect()
        self.conn = old_con.conn
        self.curosrdiction = old_con.curosr_diction
        self.curosr2 = SqliteMultithread('resource/data.ta', autocommit=True, journal_mode="WAL")
    def execute(self, string, *args):
        try:
            if string.startswith('select'):
                return self.curosrdiction.execute(string, *args)
            else:
                return self.curosr2.execute(string, *args)
        except Exception:
            print("失败一次")
            print(string)
            time.sleep(0.1)
            self.execute(string, *args)
    def executescript(self, string):
        result = True
        try:
            self.curosrdiction.executescript(string)
        except Exception:
            print("失败一次")
            # print(string)
            time.sleep(0.1)
            # self.executescript(string)
            result = False
        return result
    def fetchall(self):
        return self.curosrdiction.fetchall()
    def fetchone(self):
        return self.curosrdiction.fetchone()
    def rowcount(self):
        return self.curosrdiction.rowcount
    def select_all_dict(self, string, *args):
        return self.curosr2.select_all_dict(string, *args)
    def select_one_dict(self, string, *args):
        return self.curosr2.select_one_dict(string, *args)
    def close(self):
        self.curosr2.running = False
        self.curosrdiction.close()
        self.conn.close()
    def commit(self):
        self.conn.commit()
        self.curosr2.commit()
# curosr = Cursor()
curosr_diction = Curosrdiction()
def commit():
    curosr_diction.commit()
def close_db():
    # curosr.close()
    curosr_diction.close()