#2 error in close DB transaction

[Yura]

sometimes very rarly there is an error, sometimes followed by more errors.
this causes a leak of a ManagerStatistics mbean

2022-02-05 06:20:53 WARNING: endTransaction close error JPAInteraction 1644042045657 org.datanucleus.api.jpa.JPAEntityManager@6c9aa7f1 org.datanucleus.api.jpa.JPAEntityTransaction@2ab5ad39
javax.persistence.PersistenceException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at org.datanucleus.api.jpa.NucleusJPAHelper.getJPAExceptionForNucleusException(NucleusJPAHelper.java:317)
at org.datanucleus.api.jpa.JPAEntityManager.close(JPAEntityManager.java:200)
at net.yura.lobby.database.impl.JPADatabase.endTransaction(JPADatabase.java:108)
at net.yura.lobby.server.GameLobby$5.needInputFrom(GameLobby.java:1567)
at net.yura.lobby.server.TurnBasedGame.getInputFromClient(TurnBasedGame.java:139)
at net.yura.domination.lobby.server.ServerGameRisk.getInputFromSomeone(ServerGameRisk.java:442)
at net.yura.domination.lobby.server.ServerRisk.getInput(ServerRisk.java:140)
at net.yura.domination.engine.Risk.inGameParser(Risk.java:2044)
at net.yura.domination.lobby.server.ServerRisk.inGameParser(ServerRisk.java:135)
at net.yura.domination.lobby.server.ServerRisk.run(ServerRisk.java:109)
Caused by: java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:110)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73)
at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:898)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at org.datanucleus.store.rdbms.datasource.dbcp.DriverManagerConnectionFactory.createConnection(DriverManagerConnectionFactory.java:78)
at org.datanucleus.store.rdbms.datasource.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
at org.datanucleus.store.rdbms.datasource.dbcp.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1156)
at org.datanucleus.store.rdbms.datasource.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:108)
at org.datanucleus.store.rdbms.ConnectionProviderPriorityList.getConnection(ConnectionProviderPriorityList.java:57)
at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:403)
at org.datanucleus.store.rdbms.SQLController.getStatementForQuery(SQLController.java:312)
at org.datanucleus.store.rdbms.SQLController.getStatementForQuery(SQLController.java:296)
at org.datanucleus.store.rdbms.request.FetchRequest.execute(FetchRequest.java:324)
at org.datanucleus.store.rdbms.RDBMSPersistenceHandler.fetchObject(RDBMSPersistenceHandler.java:319)
at org.datanucleus.state.AbstractStateManager.loadFieldsFromDatastore(AbstractStateManager.java:1145)
at org.datanucleus.state.StateManagerImpl.loadUnloadedFieldsInFetchPlan(StateManagerImpl.java:2701)
at org.datanucleus.state.StateManagerImpl.detach(StateManagerImpl.java:3546)
at org.datanucleus.ExecutionContextImpl.close(ExecutionContextImpl.java:457)
at org.datanucleus.api.jpa.JPAEntityManager.close(JPAEntityManager.java:196)
... 8 more
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure</init>

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.GeneratedConstructorAccessor330.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89)
at com.mysql.cj.NativeSession.connect(NativeSession.java:119)
at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:842)
... 29 more
Caused by: java.net.ConnectException: Connection refused (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:607)
at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:156)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63)
... 31 more