Timeouts connecting to a Postgres database on Amazon RDS from Azure

问题

I get the following exception in my application after leaving a database connection idle for some amount of time:

... An I/O error occured while sending to the backend.; nested exception is org.postgresql.util.PSQLException: An I/O error occured while sending to the backend.] with root cause

    java.net.SocketException: Operation timed out
        at java.net.SocketInputStream.socketRead0(Native Method)

The same issue happens in psql AND I don't have issues connecting to a local database, so I'm pretty sure the problem is on RDS.

psql=> select 'ok';
SSL SYSCALL error: Operation timed out
psql=> select 'ok';
SSL SYSCALL error: EOF detected
The connection to the server was lost. Attempting reset: Succeeded.

I found this other question which suggests a work around that improved the situation (timeouts now take a lot longer) but didn't fix it.

I'm using Spring Boot with JDBC (tomcat connection pooling) and JDBCTemplate.

Is there a work around or a fix? Perhaps forcing the connection pool to test and reconnect? How do I do that in this environment?

EDIT: This is my connection string

jdbc:postgresql://myhost.c2estvxozjm3.eu-west-1.rds.amazonaws.com/dashboard?tcpKeepAlive=true

SOLUTION:

Edited the RDS server side TCP_KeepAlive parameters as suggested in the selected answer. The parameters I'm using are:

tcp_keepalives_count      5
tcp_keepalives_idle     200
tcp_keepalives_interval 200

回答1:

It looks like something - maybe a NAT router on your end, maybe something on AWS's end - is connection tracking, and is forgetting about connections after a while.

I suggest enabling TCP keepalives. You might be able to enable them server side in the AWS RDS configuration; if not, you can request them client-side in the JDBC driver.

TCP keepalives are a lot better than a validation/test query, because they're much lower overhead, and they don't result in unnecessary log spam in the server query logs.

回答2:

Maybe try

spring.datasource.validation-query=SELECT 1
spring.datasource.test-on-borrow=true

(See AbstractDataSourceConfiguration for other options.)

回答3:

In your connection string are you also including the port or just the endpoint? Try using the entire endpoint in your connection string. Also check to make sure the security group assigned to the RDS instance has the proper ports and Inbound CIDR defined.

来源：https://stackoverflow.com/questions/22696745/timeouts-connecting-to-a-postgres-database-on-amazon-rds-from-azure