Update: I was able to create a test that results in the same two errors.
Please find the attached file.
Note that the exceptions do not happen every run, so you may need to run it
a number of times for them to appear.
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import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class TestMultiThreadingH2 {
private static final String JDBC_URL = "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1;MULTI_THREADED=1;";
public static void main(String[] args) throws Exception {
Class.forName("org.h2.Driver");
// create some common tables and views
Connection conn = DriverManager.getConnection(JDBC_URL, "sa", "");
Statement stat = conn.createStatement();
stat.execute("CREATE TABLE INVOICE(INVOICE_ID INT PRIMARY KEY, AMOUNT DECIMAL)");
stat.execute("CREATE VIEW INVOICE_VIEW as SELECT * FROM INVOICE");
stat.execute("CREATE TABLE INVOICE_DETAIL(DETAIL_ID INT PRIMARY KEY, INVOICE_ID INT, DESCRIPTION VARCHAR)");
stat.execute("CREATE VIEW INVOICE_DETAIL_VIEW as SELECT * FROM INVOICE_DETAIL");
stat.close();
conn.close();
// create views that reference the common views in different threads
ExecutorService executor = Executors.newFixedThreadPool(8);
for (int i = 0; i < 30000; i++) {
final int j = i;
executor.execute(() -> {
Connection conn2;
try {
conn2 = DriverManager.getConnection(JDBC_URL, "sa", "");
Statement stat2 = conn2.createStatement();
stat2.execute("CREATE VIEW INVOICE_VIEW" + j + " as SELECT * FROM INVOICE_VIEW");
// the following query intermittently results in a NullPointerException
stat2.execute("CREATE VIEW INVOICE_DETAIL_VIEW" + j + " as SELECT DTL.* FROM INVOICE_VIEW" + j +
" INV JOIN INVOICE_DETAIL_VIEW DTL ON INV.INVOICE_ID = DTL.INVOICE_ID" +
" WHERE DESCRIPTION='TEST'");
ResultSet rs = stat2.executeQuery("SELECT * FROM INVOICE_VIEW" + j);
rs.next();
rs.close();
rs = stat2.executeQuery("SELECT * FROM INVOICE_DETAIL_VIEW" + j);
rs.next();
rs.close();
stat.close();
conn.close();
} catch (Exception e) {
System.out.println("exception at iteration "+j+":\n");
e.printStackTrace();
}
});
}
executor.shutdown();
try {
executor.awaitTermination(24, TimeUnit.HOURS);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
