B4J Question MySQL error (seems to time out)

[aidymp]

Hi I use the Email Server example, and modified it to update a MySQL database. the program always works fine for a few hours, but after a while maybe 12 hours or so it crashes with this log message

Spoiler: Log

main._handlemessage (java line: 515)
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 35,729,540 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3589)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3478)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4019)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2490)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2651)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2734)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1379)
at anywheresoftware.b4j.objects.SQL.ExecNonQuery2(SQL.java:193)
at ReplyMatic.aidy.main._handlemessage(main.java:515)
at ReplyMatic.aidy.main._pop_downloadcompleted(main.java:687)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:93)
at anywheresoftware.b4a.BA$3.run(BA.java:178)
at com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$149(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3039)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3489)
... 23 more

Do i need to initialise the MYSQL each time i want to add something, or just at the beginning like im already doing?

Thanks

Aidy

 

[Erel]

How are you connecting to the database? You should use ConnectionPool.

 

[jmon]

It must be after 8 hours. MySQL closes idle connections after that amount of inactivity. As Erel said, using the connection pool solved the problem for me:
https://www.b4x.com/android/forum/t...wed-after-resultset-closed.42516/#post-258144

 

[aidymp]

Is ConnectionPool part of some library? I just get unknown member : pool (b4j)

with the code

Private sql1 As SQL = Pool.GetConnection

Thanks

Aidy

 

[billzhan]

jServer lib. See the demo :
https://www.b4x.com/android/forum/threads/webapp-web-apps-overview.39811/