PostgreSQL Evolutions:"PSQLException:致命:抱歉,已经有太多客户"

Question

我正在尝试建立一个开发PostgreSQL服务器.它正在运行,我可以从命令行创建角色,表等.但是当我尝试使用Play应用evolution时,我收到以下错误:

org.postgresql.util.PSQLException: FATAL: sorry, too many clients already

我能够连接,如果我故意输入语法错误,它会返回语法错误,所以我知道Play能够连接到数据库.但是,在演变成功应用后,我得到上面显示的错误.

我对PostgreSQl管理并不十分精通,所以我不确定问题是Play还是我的PostgreSQL安装.我刚刚在运行Mountain Lion的Mac上使用Heroku的Postgres.app安装它.

这是写入控制台的内容:

! @6cnb0blpp - Internal server error, for request [GET /] ->

play.api.db.evolutions.InvalidDatabaseRevision: Database 'default' needs evolution! [An SQL script need to be run on your database.]
    at play.api.db.evolutions.EvolutionsPlugin$$anonfun$onStart$1$$anonfun$apply$1.apply$mcV$sp(Evolutions.scala:427) ~[play_2.9.1.jar:2.0.4]
    at play.api.db.evolutions.EvolutionsPlugin.withLock(Evolutions.scala:448) ~[play_2.9.1.jar:2.0.4]
    at play.api.db.evolutions.EvolutionsPlugin$$anonfun$onStart$1.apply(Evolutions.scala:414) ~[play_2.9.1.jar:2.0.4]
    at play.api.db.evolutions.EvolutionsPlugin$$anonfun$onStart$1.apply(Evolutions.scala:412) ~[play_2.9.1.jar:2.0.4]
    at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59) ~[scala-library.jar:0.11.3]
    at scala.collection.immutable.List.foreach(List.scala:45) ~[scala-library.jar:0.11.3]
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 10. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 9. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 8. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 7. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 6. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 5. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 4. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 3. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 2. Exception: null
[error] c.j.b.h.AbstractConnectionHook - Failed to acquire connection Sleeping for 1000ms and trying again. Attempts left: 1. Exception: null
[error] application - 

谢谢!

Answer 1

postgresql.conf使用GUC("Grand Unified Configuration")设置允许的连接数max_connections.默认值为100.

但是,在你修改设置之前,你必须问自己:在你的集群达到极限之前,所有其他100个连接的来源是什么？这通常指向您的安装或程序中的错误!

您可能还对连接池和本文关于 Postgres Wiki中的连接数感兴趣.

Answer 2

您可以减少应用程序使用的连接数。mac安装也有同样的错误。如官方文档所示：

db.default.partitionCount=2

# The number of connections to create per partition. Setting this to 
# 5 with 3 partitions means you will have 15 unique connections to the 
# database. Note that BoneCP will not create all these connections in   
# one go but rather start off with minConnectionsPerPartition and 
# gradually increase connections as required.
db.default.maxConnectionsPerPartition=5

# The number of initial connections, per partition.
db.default.minConnectionsPerPartition=5