nodejs pg-pool 似乎没有池化

如何解决nodejs pg-pool 似乎没有池化

我一直试图让 nodejs 在我的应用程序中汇集 postgresql 连接，但没有成功。这是我所做的独立测试：

const config = require('../config/project_config.json');
const Pool = require('pg-pool');

var pool = new Pool({
    user: config.DB_USER,host: config.DB_HOST,database: config.DB_DB,password: config.DB_PW,port: 5432,max: 500,min: 200,idleTimeoutMillis: 0,connectionTimeoutMillis: 10000
});

for (var i=0; i<100; i++){
    pool.query(
        "SELECT id,email FROM players WHERE email ~ 'ltUser'",[],(err,res) => {
            if (err !== null && err != undefined){
                console.log(`err: ${err}`);
            }
            else{
                console.log(`num rows: ${res.rows.length}`);
            }
        });
}

我得到的结果是：

num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
err: Error: Connection terminated due to connection timeout
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400
num rows: 400

如您所见，它抛出连接超时，这意味着在我创建池时它没有创建连接。在创建池时，我尝试了各种参数组合，包括使用 keepalive: true，但似乎没有一个使 pg-pool 实际上池连接。我也试过 pg 而不是 pg-pool。但得到了完全相同的结果，尽管我后来发现它们基本上是相同的代码。

如果我用更长的查询运行它，我可以在 psql 中连接到数据库并运行

SELECT datname,usename,ssl,client_addr,count(*
FROM pg_stat_ssl
  JOIN pg_stat_activity
    ON pg_stat_ssl.pid = pg_stat_activity.pid
where usename != 'azure_superuser'
group by datname,client_addr;

并观察我的 IP 地址的连接数上升然后再次下降。

是我做错了什么还是 pg-pool 坏了？

我在 ubuntu xenial 服务器上使用 nodejs v10.22.1。

解决方法

事实证明 pg-pool 可以正常工作，只是根据我在其他编程语言（如 Java 和 Erlang）方面的经验，不是我所期望的方式。 Nodejs 不会提前创建连接，而是在连接从池中检出时创建。

基于此，Nodejs 中池化的主要优点是程序员不必处理打开和关闭连接，并且可以重复使用这些连接。