psql：致命错误：剩余的连接插槽保留用于非复制超级用户连接 [英] psql: FATAL: remaining connection slots are reserved for non-replication superuser connections

问题描述

我想了解何时发生此错误以及如何解决。我检查了 pg_stat_activity 和 pg_locks ，但无法弄清哪个进程正在耗尽连接

I want to understand when this error occurs and how to resolve it. I checked pg_stat_activity and pg_locks but couldnt figure out which process is exhausing the connections

我们正在使用sqlalchemy如下连接数据库

We are using sqlalchemy to connect to database as below

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

engine_url = f'{dbms}://{username}:{password}@{hostname}:{port}/{database}'

engine = create_engine(engine_url, pool_size=20, max_overflow=10)
Session = sessionmaker(bind=engine)

db_session = Session()

这是 Heroku psql：致命：剩余的连接插槽保留用于非复制超级用户连接

推荐答案

I我在sqlalchemy引擎url的应用程序名称中添加了客户端进程ID。这将存储在 pg_stat_activity 中的 application_name 下，这对于从打开此连接的位置进行调试将很有帮助。 / p>

I am adding the client process id in application name of sqlalchemy engine url. This will be stored under application_name in pg_stat_activity and it will be helpful to debug from where did this connection was opened.

import os
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

client_hostname = os.environ.get('HOSTNAME', 'UNKNOWN')
client_pid = os.getpid()


engine_url = f'{dbms}://{username}:{password}@{hostname}:{port}/{database}?application_name={client_hostname}_{client_pid}'

engine = create_engine(engine_url, pool_size=20, max_overflow=10)
Session = sessionmaker(bind=engine)

db_session = Session()

连接起源的地方，应用程序名称的限制为 64个字符，因此我们可以包含要传递给数据库统计信息的所有自定义信息

This shows where the connection was originated from and the application name has a limit of 64 chars, so we can include any custom information that you want to pass on to db stats

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