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我的代碼是用jruby編寫的，我使用warbler在tomcat中部署。我正在使用SEQUEL來查詢mysql數據庫。我正在使用兩層數據庫連接池。一個是本地SEQUEL池，另一個是在tomcat級別的JNDI池。連接字符串是：面對NativeException：java.sql.SQLException：連接[email protected]已關閉
DB = Sequel.connect("jdbc:jndi:java:comp/env/test", :logger => $db_log, :max_connections => 10)
此連接字符串在app.rb其中被加載時，纔會有新的部署或Tomcat啓動定義。這將創建一個續集連接池，並且所有線程共享此池。 在我的$ CATALINA_OME/conf/context.xml文件的JNDI配置如下：
<Resource
name="test"
auth="Container"
type="javax.sql.DataSource"
maxActive="10"
maxIdle="5"
maxWait="9000"
username="test_db"
password="test_db"
driverClassName="com.mysql.jdbc.Driver"
testOnBorrow="true"
testWhileIdle="true"
validationQuery="SELECT 1" testOnReturn="true"
timeBetweenEvictionRunsMillis="300000" removeAbandonedTimeout="60"
removeAbandoned="true"
logAbandoned="true"
url="jdbc:mysql://IP:3306/test"
/>
我使用DB.disconnect返回JNDI池連接，以確保沒有線程使用的是先前用於連接。我正在這樣做，以確保wait_timeout錯誤。 「auto_reconnect = true」似乎沒有正確解決wait_timeout問題。 一切都是直到幾天工作正常，回來時，我突然開始得到這樣的錯誤：
W, [2012-07-26T05:10:30.999000 #29456] WARN -- : 134325951259087 == NativeException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
D, [2012-07-26T05:10:31.001000 #29456] DEBUG -- : 134325951259087 == ["sun.reflect.GeneratedConstructorAccessor23:-1:in `newInstance'", "sun/reflect/DelegatingConstructorAccessorImpl.java:27:in `newInstance'", "java/lang/reflect/Constructor.java:513:in `newInstance'", "com/mysql/jdbc/Util.java:409:in `handleNewInstance'", "com/mysql/jdbc/SQLError.java:1118:in `createCommunicationsException'", "com/mysql/jdbc/MysqlIO.java:343:in `<init>'", "com/mysql/jdbc/ConnectionImpl.java:2308:in `connectOneTryOnly'", "com/mysql/jdbc/ConnectionImpl.java:2122:in `createNewIO'", "com/mysql/jdbc/ConnectionImpl.java:774:in `<init>'", "com/mysql/jdbc/JDBC4Connection.java:49:in `<init>'", "sun.reflect.GeneratedConstructorAccessor25:-1:in `newInstance'", "sun/reflect/DelegatingConstructorAccessorImpl.java:27:in `newInstance'", "java/lang/reflect/Constructor.java:513:in `newInstance'", "com/mysql/jdbc/Util.java:409:in `handleNewInstance'"
&
W, [2012-07-26T10:19:14.029000 #1572] WARN -- : 134327815053548 == NativeException: java.sql.SQLException: Connection [email protected] is closed.
D, [2012-07-26T10:19:14.030000 #1572] DEBUG -- : 134327815053548 == ["org/apache/tomcat/dbcp/dbcp/DelegatingConnection.java:398:in `checkOpen'", "org/apache/tomcat/dbcp/dbcp/DelegatingConnection.java:255:in `createStatement'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/adapters/jdbc.rb:523:in `statement'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/adapters/jdbc.rb:233:in `execute'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/connection_pool/threaded.rb:88:in `hold'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/database/connecting.rb:234:in `synchronize'", "file:/usr/local/tomcat-instance/testv/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/adapters/jdbc.rb:232:in `execute'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/lib/santa-gems.jar!/gems/sequel-3.34.0/lib/sequel/dataset/actions.rb:744:in `execute'", "file:/usr/local/tomcat-instance/test/webapps/service/WEB-INF/l
而且，這些錯誤也經常發生被忽略。 發生在沒有任何錯誤的時間和現在是數據庫主機的變化之間發生的唯一變化。但是我確定超時變量保持不變。值爲：
interactive_timeout=300
connect_timeout=300
wait_timeout=10
還有什麼可以創造差異？