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From "Oilid Adsi" <Oilid.A...@mobilcom.de>
Subject AW: Crash when reconnecting to MySQL (3.0M3)
Date Wed, 26 Mar 2008 09:38:01 GMT
Hi Andrus, Alex,

the mysql-docu says at:
http://dev.mysql.com/doc/refman/5.1/en/connector-j-reference-configuration-properties.html


"The use of this feature is not recommended, because it has side effects related to session
state and data consistency when applications don't handle SQLExceptions properly, and is only
designed to be used when you are unable to configure your application to handle SQLExceptions
resulting from dead and stale connections properly"

Sometimes I saw the same exception-stack like Alex one in my application.
But I didn't want to use "autoReconnect=true" because of the comment above.

So maybe that is not the right solution.

Greetings
Oilid

-----Ursprüngliche Nachricht-----
Von: Andrus Adamchik [mailto:andrus@objectstyle.org] 
Gesendet: Mittwoch, 26. März 2008 10:27
An: user@cayenne.apache.org
Betreff: Re: Crash when reconnecting to MySQL (3.0M3)

Are you using "autoReconnect=true" parameter in the MySQL connection  
URL?

Thanks,
Andrus


On Mar 26, 2008, at 10:44 AM, Alexander Lamb wrote:

> Hello List,
>
> We have an application, deployed successfully with Tapestry 5.0.11  
> and Cayenne 3.0M3 on Tomcat 6 with MySQL 5.0.
>
> Everything is fine until the point where a long period of inactivity  
> has passed and (we suppose) all the DataContexts are garbage  
> collected (we create one DataContext per user session).
> The first user who logs in will generate an error on (again, what we  
> suppose) is a problem reconnecting to MySQL.
>
> To avoid the problem, we "ping" the app to keep it alive... We also  
> tried to catch the Exception but doing so simply pushes the problem  
> to another part of the program. The funny thing is that it is not  
> the first attempt to connect to the database but maybe the first  
> attempt using either a stored query in the model or raw SQL.
>
> Here is the kind of message we get:
>
> 	Communications link failure due to underlying exception:
>
> ** BEGIN NESTED EXCEPTION **
>
> java.io.EOFException
>
> STACKTRACE:
>
> java.io.EOFException
> 	at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1905)
> 	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2351)
> 	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2862)
> 	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1571)
> 	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1666)
> 	at com.mysql.jdbc.Connection.execSQL(Connection.java:2988)
> 	at com.mysql.jdbc.Connection.setAutoCommit(Connection.java:4913)
> 	at  
> org 
> .apache 
> .cayenne 
> .conn.PooledConnectionImpl.getConnection(PooledConnectionImpl.java: 
> 129)
> 	at  
> org 
> .apache.cayenne.conn.PoolManager.uncheckConnection(PoolManager.java: 
> 383)
> 	at  
> org.apache.cayenne.conn.PoolManager.getConnection(PoolManager.java: 
> 367)
> 	at  
> org.apache.cayenne.conn.PoolManager.getConnection(PoolManager.java: 
> 344)
> 	at org.apache.cayenne.access.DataNode 
> $TransactionDataSource.getConnection(DataNode.java:321)
> 	at org.apache.cayenne.access.DataNode.performQueries(DataNode.java: 
> 209)
> 	at  
> org 
> .apache 
> .cayenne 
> .access.DataDomainQueryAction.runQuery(DataDomainQueryAction.java:442)
> 	at org.apache.cayenne.access.DataDomainQueryAction.access 
> $000(DataDomainQueryAction.java:67)
> 	at org.apache.cayenne.access.DataDomainQueryAction 
> $2.transform(DataDomainQueryAction.java:415)
> 	at  
> org 
> .apache.cayenne.access.DataDomain.runInTransaction(DataDomain.java: 
> 847)
> 	at  
> org 
> .apache 
> .cayenne 
> .access 
> .DataDomainQueryAction 
> .runQueryInTransaction(DataDomainQueryAction.java:412)
> 	at  
> org 
> .apache 
> .cayenne 
> .access.DataDomainQueryAction.execute(DataDomainQueryAction.java:119)
> 	at org.apache.cayenne.access.DataDomain.onQuery(DataDomain.java:740)
> 	at  
> org 
> .apache 
> .cayenne 
> .util 
> .ObjectContextQueryAction.runQuery(ObjectContextQueryAction.java:296)
> 	at org.apache.cayenne.util.ObjectContextQueryAction 
> $1.createObject(ObjectContextQueryAction.java:286)
> 	at org.apache.cayenne.cache.MapQueryCache.get(MapQueryCache.java:74)
> 	at  
> org 
> .apache 
> .cayenne 
> .util 
> .ObjectContextQueryAction 
> .interceptLocalCache(ObjectContextQueryAction.java:258)
> 	at  
> org 
> .apache 
> .cayenne 
> .util.ObjectContextQueryAction.execute(ObjectContextQueryAction.java: 
> 82)
> 	at org.apache.cayenne.access.DataContext.onQuery(DataContext.java: 
> 1331)
> 	at  
> org.apache.cayenne.access.DataContext.performQuery(DataContext.java: 
> 1320)
> 	at  
> ch 
> .rodano 
> .studies 
> .services 
> .StudySession 
> .getRunningTotalPatientsByMonthForRegistryCenters(StudySession.java: 
> 466)
>
>
> etc...
>
> Thanks for any idea!
>
> Alex
>
> --
> Alexander Lamb
> Founding Associate
> RODANOTECH Sàrl
>
> 4 ch. de la Tour de Champel
> 1206 Geneva
> Switzerland
>
> Tel:  022 347 77 37
> Fax: 022 347 77 38
>
> http://www.rodanotech.ch
>
>
>
>


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