Python实现 多进程导入CSV数据到 MySQL

前段时间帮同事处理了一个把 CSV 数据导入MySQL 的需求。两个很大的 CSV 文件, 分别有 3GB、2100 万条记录和 7GB、3500 万条记录。对于这个量级的数据,用简单的单进程/单线程导入 会耗时很久,最终用了多进程的方式来实现。具体过程不赘述,记录一下几个要点:

  1. 批量插入而不是逐条插入
  2. 为了加快插入速度,先不要建索引
  3. 生产者和消费者模型,主进程读文件,多个 worker 进程执行插入
  4. 注意控制 worker 的数量,避免对 MySQL 造成太大的压力
  5. 注意处理脏数据导致的异常
  6. 原始数据是 GBK 编码,所以还要注意转换成 UTF-8
  7. 用 click 封装命令行工具

具体的代码实现如下:

?

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

#!/usr/bin/env python

# -*- coding: utf-8 -*-

import codecs

import csv

import logging

import multiprocessing

import os

import warnings

import click

import MySQLdb

import sqlalchemy

warnings.filterwarnings('ignore', category=MySQLdb.Warning)

# 批量插入的记录数量

BATCH = 5000

DB_URI = 'mysql://root@localhost:3306/example?charset=utf8'

engine = sqlalchemy.create_engine(DB_URI)

def get_table_cols(table):

sql = 'SELECT * FROM `{table}` LIMIT 0'.format(table=table)

res = engine.execute(sql)

return res.keys()

def insert_many(table, cols, rows, cursor):

sql = 'INSERT INTO `{table}` ({cols}) VALUES ({marks})'.format(

table=table,

cols=', '.join(cols),

marks=', '.join(['%s'] * len(cols)))

cursor.execute(sql, *rows)

logging.info('process %s inserted %s rows into table %s', os.getpid(), len(rows), table)

def insert_worker(table, cols, queue):

rows = []

# 每个子进程创建自己的 engine 对象

cursor = sqlalchemy.create_engine(DB_URI)

while True:

row = queue.get()

if row is None:

if rows:

insert_many(table, cols, rows, cursor)

break

rows.append(row)

if len(rows) == BATCH:

insert_many(table, cols, rows, cursor)

rows = []

def insert_parallel(table, reader, w=10):

cols = get_table_cols(table)

# 数据队列,主进程读文件并往里写数据,worker 进程从队列读数据

# 注意一下控制队列的大小,避免消费太慢导致堆积太多数据,占用过多内存

queue = multiprocessing.Queue(maxsize=w*BATCH*2)

workers = []

for i in range(w):

p = multiprocessing.Process(target=insert_worker, args=(table, cols, queue))

p.start()

workers.append(p)

logging.info('starting # %s worker process, pid: %s...', i + 1, p.pid)

dirty_data_file = './{}_dirty_rows.csv'.format(table)

xf = open(dirty_data_file, 'w')

writer = csv.writer(xf, delimiter=reader.dialect.delimiter)

for line in reader:

# 记录并跳过脏数据: 键值数量不一致

if len(line) != len(cols):

writer.writerow(line)

continue

# 把 None 值替换为 'NULL'

clean_line = [None if x == 'NULL' else x for x in line]

# 往队列里写数据

queue.put(tuple(clean_line))

if reader.line_num % 500000 == 0:

logging.info('put %s tasks into queue.', reader.line_num)

xf.close()

# 给每个 worker 发送任务结束的信号

logging.info('send close signal to worker processes')

for i in range(w):

queue.put(None)

for p in workers:

p.join()

def convert_file_to_utf8(f, rv_file=None):

if not rv_file:

name, ext = os.path.splitext(f)

if isinstance(name, unicode):

name = name.encode('utf8')

rv_file = '{}_utf8{}'.format(name, ext)

logging.info('start to process file %s', f)

with open(f) as infd:

with open(rv_file, 'w') as outfd:

lines = []

loop = 0

chunck = 200000

first_line = infd.readline().strip(codecs.BOM_UTF8).strip() + '\n'

lines.append(first_line)

for line in infd:

clean_line = line.decode('gb18030').encode('utf8')

clean_line = clean_line.rstrip() + '\n'

lines.append(clean_line)

if len(lines) == chunck:

outfd.writelines(lines)

lines = []

loop += 1

logging.info('processed %s lines.', loop * chunck)

outfd.writelines(lines)

logging.info('processed %s lines.', loop * chunck + len(lines))

@click.group()

def cli():

logging.basicConfig(level=logging.INFO,

format='%(asctime)s - %(levelname)s - %(name)s - %(message)s')

@cli.command('gbk_to_utf8')

@click.argument('f')

def convert_gbk_to_utf8(f):

convert_file_to_utf8(f)

@cli.command('load')

@click.option('-t', '--table', required=True, help='表名')

@click.option('-i', '--filename', required=True, help='输入文件')

@click.option('-w', '--workers', default=10, help='worker 数量,默认 10')

def load_fac_day_pro_nos_sal_table(table, filename, workers):

with open(filename) as fd:

fd.readline() # skip header

reader = csv.reader(fd)

insert_parallel(table, reader, w=workers)

if __name__ == '__main__':

cli()

以上就是本文给大家分享的全部没人了,希望大家能够喜欢

原文链接:http://liyangliang.me/posts/2017/02/load-data-into-mysql-using-python-multiprocessing/

本文链接:https://my.lmcjl.com/post/14744.html

展开阅读全文

4 评论

留下您的评论.