问题描述
我在Windows 10（i7-9700K cpu 3.60 GHz）ram 16 Go上将MysqL 5.7.24与Laragon一起使用。 通过Anaconda + MysqL Connector 8.0.18的Python 3.7。 我正在对数据库进行一些查询和更新，该数据库有1200万行用于最大的表。
我创建了一个循环（带有缓冲的和准备好的游标），该循环当时占用1000行，然后进行计算和更新，然后关闭连接。最后，如果数据库中仍有行要更新（我为此有一个布尔值），则循环将调用自身，每个循环都将关闭每个游标和连接，并使用新的连接重新启动。
但是，内存永远不会释放，并且每次4到5个小时后我的PC都会冻结。 我已经阅读了有关该主题的一些信息，但是尚不清楚是错误还是其他原因。
您有什么建议？谢谢
import MysqL.connector
from MysqL.connector import errorcode
def main():
CONNECTION_STRING = {
'user': 'user','passwd': 'pass','host': 'localhost','database': 'my_database','raise_on_warnings': True
}
try:
cnx = MysqL.connector.connect(**CONNECTION_STRING)
except MysqL.connector.Error as err:
if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
print("Something is wrong with your user name or password")
elif err.errno == errorcode.ER_BAD_DB_ERROR:
print("Database does not exist")
else:
print(err)
else:
print("Vous êtes connecté")
curGet = cnx.cursor(buffered=True)
curU = cnx.cursor(prepared=True)
curS2 = cnx.cursor()
curS3 = cnx.cursor()
# queries
get_cheval = ('''
SELECT cheval.id as cId,cheval.nom_pt as nPt
FROM cheval
WHERE nom_pt IS NOT NULL
AND nom IS NULL
LIMIT 1000
;''')
update_cheval = ('''
UPDATE cheval
SET nom = %s,pays_id = %s
WHERE id = %s
;''')
select_contry_alpah2 = ('''
SELECT id FROM pays
WHERE alpha2_pt = %s
;''')
select_contry_alpha3 = ('''
SELECT id pId FROM pays
WHERE alpha3_pt = %s
;''')
curGet.execute(get_cheval)
list_alpha2_ignore = ['II','IV','VI','JR',]
list_alpha3_ignore = ['VII','III',"J'R",'XYZ']
is_there_row = False # for the loop
for (cId,nPt) in curGet:
is_there_row = True
split_nom_pt = nPt.strip().split(' ')
print(split_nom_pt)
contry = split_nom_pt[-1].replace('(','').replace(')','')
if contry.isupper() and len(contry) == 3 and contry not in list_alpha3_ignore:
curS3.execute(select_contry_alpha3,(contry,))
pays_id_tmp = curS3.fetchone()
if pays_id_tmp is not None:
pays_id = pays_id_tmp[0]
else:
pays_id = None
if pays_id is not None:
nom = ' '.join(split_nom_pt[:-1])
else:
nom = None
elif contry.isupper() and len(contry) == 2 and contry not in list_alpha2_ignore:
curS2.execute(select_contry_alpah2,))
pays_id_tmp = curS2.fetchone()
if pays_id_tmp is not None:
pays_id = pays_id_tmp[0]
else:
pays_id = None
if pays_id is not None:
nom = ' '.join(split_nom_pt[:-1])
else:
nom = None
else:
pays_id = 75
nom = nPt.strip()
curU.execute(update_cheval,(nom,pays_id,cId))
cnx.commit()
print('updated:' + str(nom) + '; ' + str(pays_id))
curGet.close()
curS2.close()
curS3.close()
curU.close()
cnx.close()
# LOOP
if is_there_row:
is_there_row = False
main()
else:
print('End')
if __name__ == '__main__':
main()
解决方法
正如我在评论中说的那样，代码正在泄漏内存，因为您只能在所有调用返回后才完成第一个main，考虑到无法从内存中删除函数变量。
import mysql.connector
from mysql.connector import errorcode
# First suggestion: Move constants outside of the function
# this way they'll be created only once
connection_string = {
'user': 'user','passwd': 'pass','host': 'localhost','database': 'my_database','raise_on_warnings': True
}
# queries
get_cheval = ('SELECT cheval.id as cId,cheval.nom_pt as nPt'
'FROM cheval'
'WHERE nom_pt IS NOT NULL'
'AND nom IS NULL'
'LIMIT 1000;') # Maybe you're missing an offset here? This query should always return the same first 1000 results. (Maybe you're updating the horses so that they don't match the query thought)
update_cheval = ('UPDATE cheval'
'SET nom = %s,pays_id = %s'
'WHERE id = %s;')
select_contry_alpah2 = ('SELECT id FROM pays'
'WHERE alpha2_pt = %s;')
select_contry_alpha3 = ('SELECT id pId FROM pays'
'WHERE alpha3_pt = %s;')
def main():
done=False
while not done:
try:
cnx = mysql.connector.connect(**connection_string)
except mysql.connector.Error as err:
if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
print("Something is wrong with your user name or password")
elif err.errno == errorcode.ER_BAD_DB_ERROR:
print("Database does not exist")
else:
print(err)
continue # Go back and try again
print("Vous êtes connecté")
curGet = cnx.cursor(buffered=True)
curU = cnx.cursor(prepared=True)
curS2 = cnx.cursor()
curS3 = cnx.cursor()
while cnx.is_connected():
curGet.execute(get_cheval)
result = curGet.fetchone()
if result is None:
done = True
break;
list_alpha2_ignore = ['II','IV','VI','JR',]
list_alpha3_ignore = ['VII','III',"J'R",'XYZ']
for (cId,nPt) in curGet:
split_nom_pt = nPt.strip().split(' ')
print(split_nom_pt)
contry = split_nom_pt[-1].replace('(','').replace(')','')
if contry.isupper() and len(contry) == 3 and contry not in list_alpha3_ignore:
curS3.execute(select_contry_alpha3,(contry,))
pays_id_tmp = curS3.fetchone()
if pays_id_tmp is not None:
pays_id = pays_id_tmp[0]
else:
pays_id = None
if pays_id is not None:
nom = ' '.join(split_nom_pt[:-1])
else:
nom = None
elif contry.isupper() and len(contry) == 2 and contry not in list_alpha2_ignore:
curS2.execute(select_contry_alpah2,))
pays_id_tmp = curS2.fetchone()
if pays_id_tmp is not None:
pays_id = pays_id_tmp[0]
else:
pays_id = None
if pays_id is not None:
nom = ' '.join(split_nom_pt[:-1])
else:
nom = None
else:
pays_id = 75
nom = nPt.strip()
curU.execute(update_cheval,(nom,pays_id,cId))
cnx.commit()
print('updated:' + str(nom) + '; ' + str(pays_id))
curGet.close()
curS2.close()
curS3.close()
curU.close()
cnx.close()
if __name__ == '__main__':
main()