Shulou(Shulou.com)06/02 Report--

This article mainly introduces "how to create python database connection pool". In daily operation, I believe many people have doubts about how to create python database connection pool. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts of "how to create python database connection pool". Next, please follow the editor to study!

1. Do not use database connection pooling, and link to the database for every operation. The number of links is too many.

Conn = pymysql.connect (host= "127.0.0.1", port=3306,user='root',password='123', database='pooldb',charset='utf8') cursor = conn.cursor () cursor.execute ("select * from td where id=%s", [5,]) result = cursor.fetchall () # get data cursor.close () conn.close () # close the link

In this way, each request creates a database link repeatedly, and it is very time-consuming to link the database multiple times.

2. Create a link pool to provide connections for all threads, get it when you use it, and put it back to the connection pool after use.

PS: suppose the maximum number of links is 10, which is actually a list. When you pop one, the system will append another. All the links in the link pool are linked according to the queued way. All the links in the link pool can be reused and shared, which not only realizes concurrency, but also prevents too many links.

Import timeimport pymysqlimport threadingfrom DBUtils.PooledDB import PooledDB, SharedDBConnectionPOOL = PooledDB (creator=pymysql, # use the module maxconnections=6 of the linked database, # the maximum number of connections allowed in the connection pool, 0 and None indicate no limit on the number of connections mincached=2, # initialize at least the free links created in the link pool, 0 means no maxcached=5 is created, and # the most idle links in the link pool 0 and None do not limit maxshared=3, the maximum number of links shared in the # link pool, and 0 and None means all are shared. PS: useless, because modules such as pymysql and MySQLdb have a threadsafety of 1, and no matter how many values are set, _ maxcached is always 0, so all links are always shared. Blocking=True, whether to block waiting if no connection is available in the connection pool. True, wait; False, do not wait and then report an error maxusage=None, # the maximum number of times a link is reused, and None represents an unlimited setsession= [], # list of commands executed before starting the session. For example, ["set datestyle to...", "set time zone..."] Ping=0, # ping MySQL server, check whether the service is available. # for example: 0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always host='127.0.0.1', port=3306, user='root', password='123', database='pooldb', charset='utf8') def func (): # check whether the number of connections currently running is less than the maximum number of links If not less than that: wait or report raise TooManyConnections exception # otherwise # priority will be given to getting the link SteadyDBConnection from the link created during initialization. # then encapsulate the SteadyDBConnection object into PooledDedicatedDBConnection and return. # if the link created at the beginning does not have a link, create a SteadyDBConnection object, encapsulate it in PooledDedicatedDBConnection, and return it. # once the link is closed, the connection returns to the connection pool for subsequent threads to continue to use. # PooledDedicatedDBConnection conn = POOL.connection () # print (th, 'the link has been taken away', conn1._con) # print (th, 'there are currently in the pool', pool._idle_cache,'\ r\ n') cursor = conn.cursor () cursor.execute ('select * from tb1') result = cursor.fetchall () conn.close () this ends the study of "how to create a python database connection pool" I hope I can solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.