Utilising ProxySQL for connection pooling in PHP

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proxysql是一个非常强大的工具，具有扩展功能。本演示将演示如何使用proxysql获得功能（无缝数据库后端交换机）并纠正问题（应用程序缺少连接池）。本演示将是一个关于如何使用proxysql进行连接池、数据库故障转移和负载平衡的实际研究，即我们的（第三方）PHP应用程序和我们的主MySQL集群之间的通信。此外，我们将使用Percona监视和管理（PMM）显示监视和统计。

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4 .The Environment • ~12k hardware clients • ~4k “software” clients (users) • ~6k qps • ~3k prepared statement calls/sec • ~500 transactions/sec • ~400 tcp open/sec • 3:rd party application, written in PHP, running on seven web servers  4 © 2018 Percona

6 .TCP States ● After Closing they stay in TIME_WAIT state. ● TIME_WAIT timeout is 1-2 minutes (the connections stay in that state.) ● cat /proc/sys/net/ipv4/ip_local_port_range - 32768 60999 ○ That is around ~ 28231 local ports. It sounds a lot ● Let’s say every connections stay there 1 minute. ○ 28231 / 60 ~ 470 , you will run out local ports if you open more than 470 connections per second. ● When you have 12k hardware clients sending data in every seconds that is not that lot. ○ PHP Warning: mysqli::mysqli(): (HY000/2002): Cannot assign requested address in / root/phptest/test_credentials.php on line 33 6 © 2018 Percona

7 .The problem(s) ● No connection pooling in PHP, leading to ● Firewall port exhaustion ● Source port exhaustion on web-servers ● High number of tcp-connection requests ● High threadpool activity ● Ineffective use of prepared statements ● 1 prepare/bind/execute/close ● small number of unique statements 7 © 2018 Percona

8 .The problem(s) ● “Closed source” - proprietary PHP ● Each page call creates one to many database sessions ● Needs to ‘co-exist’ with other critical application servers - no way of setting up an isolated environment for this application ● Business demands 24/7 uptime ● Hardware clients sends status updates only once - no resends 8 © 2018 Percona

10 .We can use PMM ● The metrics are collected. ● But they are not visualized. ● We need a custom dashboards for TCP connections. ○ rate(node_netstat_Tcp_ActiveOpens{instance=~"$host"}[$interval]) or irate(node_netstat_Tcp_ActiveOpens{instance=~"$host"}[5m]) 10 © 2018 Percona

13 .Connection Pooling ● Opening and closing a connection for each request is costly and wastes resources. ● Connection pooling is a collection of the connections. ● The application can reuse the same connection again. ● This reduces the overhead associated with connecting to the database to service individual requests. 13 © 2018 Percona

15 .Connection Pooling ● Java has connection pooling. ● Python has connection pooling. ● But PHP does not have a proper connection pooling. ○ Without connection pooling the chance to get contentions issues is significantly higher. It does not matter what kind of application do you use. 15 © 2018 Percona

17 .Possible Solutions ● rewrite PHP/port application ○ supplier unwilling to take the development cost ○ in-house development team unwilling to take maintenance responsibility ○ operations team unwilling to maintain a separate “branch” for patching ● ip-tables ○ NAT complexifies the environment ○ requires different configuration across portals ○ adds to firewall strain ● Tune kernel parameters ● Unix Sockets 17 © 2018 Percona

18 .Possible Solutions - Unix Sockets ● Unix domain socket or IPC socket (inter-process communication socket). ● Exchanging data between processes executing on the same host operating system. ● Rather than using an underlying network protocol, all communication occurs entirely within the operating system kernel. ● Uses the file system as their address name space. ● Two processes can communicate by opening the same socket. 18 © 2018 Percona

21 .Relevant features ● seamless integration ○ reconfigure all portals to connect to unix-socket ○ proxySQL “proxying” connections from unix-socket to backend DB ● connection pooling ○ application closes connection to proxySQL, not to DB ○ proxySQL reuses db-connections for the next connect ● prepared statement reuse ○ proxySQL filters out “statement close”/”prepare statement” when possible 21 © 2018 Percona

22 .The new environment ● ~12k hardware clients ● ~4k “software” clients (users) ● ~6k qps ● ~3k prepared statement calls/sec ○ ~3k “execute statement”/sec ○ ~50 “prepare statement”/sec ● ~500 transactions/sec ● ~10 tcp open/sec ● 3:rd party application, written in PHP, running on seven web servers, with locally installed proxySQL ● 1 central proxySQL for backend switch 22 © 2018 Percona

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