Jmeter does not see the variables when trying to connect to the database - jdbc

Question

I have the following problem.
When you try to create a connection can not find variables.
The test has the following set of actions
Download the local settings file (put in props)
Create a database connection (This happens all in different groups, i tried in the same)
Use next code for upload local property file(Bean Shell, Thread Group 1)
FileInputStream is = new FileInputStream(new File("d:/somefolder/somefile.properties"));
props.load(is);
is.close();
Before creating the connection I checked the availability of variables(Bean Shell, Thread Group 2)
System.out.println(props.get("db.url"));
System.out.println(${__P("db.url")});
${__setProperty("db.url", props.get("db.url"))};
System.out.println(${__P("db.url")});
OutPut
correct connection url
1(Because function __P return default value if variable undefined,
default value = 1)
correct connection url
Create Jdbc Connection with next parametrs(Thread Group 2)
url: ${__P("db.url")}
Test Failure because ${__P("db.url")} return 1
If i use ${__BeanShell(props.get(db.url))}
Test Failure because props.get(db.url) return nothing
If i use ${__javaScript(props.get(db.url))}
Test Failure because props.get(db.url) return nothing

Answer 1

"Component jdbc connection configuration" initialized before started first Thread Group, so component don't see variables because he don't initialize.
Create Script for connecting to db
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSetMetaData;
ResultSet clientConfigs = null;
ResultSet gameIds = null;
Connection connect = null;
Statement statement = null;
try {
Class.forName(props.get("configdb.driverClassName"));
String connectionUrl = props.get("configdb.url") + "?user=" + props.get("configdb.username") + "&password=" + props.get("configdb.password");
connect = DriverManager.getConnection(connectionUrl);
statement = connect.createStatement();
clientConfigs = statement.executeQuery("Select keyname,valuestr from client_config WHERE valuestr Like '%/_ah/api/%'");
ResultSetMetaData ccMetaData = clientConfigs.getMetaData();
int clientConfigsColumns = ccMetaData.getColumnCount();
ArrayList clientConfigsList = new ArrayList(20);
while (clientConfigs.next()){
HashMap clientConfigsRow = new HashMap(clientConfigsColumns);
for(int i=1; i<=clientConfigsColumns; ++i){
clientConfigsRow.put(ccMetaData.getColumnName(i), clientConfigs.getObject(i));
}
clientConfigsList.add(clientConfigsRow);
}
vars.putObject("clientConfigs", clientConfigsList);
gameIds = statement.executeQuery("Select gameId from game_config");
ResultSetMetaData giMetaData = gameIds.getMetaData();
int gameIdsColumns = giMetaData.getColumnCount();
ArrayList gameIdsList = new ArrayList(50);
while (gameIds.next()){
HashMap gameIdsRow = new HashMap(gameIdsColumns);
for(int i=1; i<=gameIdsColumns; ++i){
gameIdsRow.put(giMetaData.getColumnName(i), gameIds.getObject(i));
}
gameIdsList.add(gameIdsRow);
}
vars.putObject("gameIds", gameIdsList);
}
catch (Exception e) {
throw e;
} finally {
try {
if (clientConfigs != null) {
clientConfigs.close();
}
if (gameIds != null) {
gameIds.close();
}
if (statement != null) {
statement.close();
}
if (connect != null) {
connect.close();
}
} catch (Exception e) {
}
}

Answer 2

Apparently JMeter loads JDBC configuration parameters at really early, likely at UI load. See discussion here
The JDBC Config element is only processed at test startup, so it is
not possible to change the values once a test has started - i.e. you
could not change the values for different loops of the test plan. The
test plan has to know the JDBC settings near the start.
Which means, if you change value of property in threadGroup-1 at runtime, the changes will not take effect in JDBC config.
One possible way around this is to set the property from the command line while starting JMeter.
Alternatively drop JDBC sampler entirely and use one of the custom samplers to interact with your JDBC data source.