No errors or warnings from Hive JDBC connection - c

Question

Im trying to invoke a java program through C using JNI. The Java program is basically a JDBC connection to Hive.
Here is my code snippet
Java program
import java.sql.SQLException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DriverManager;
public class HiveJdbcClient {
private static String driverName = "org.apache.hive.jdbc.HiveDriver";
/**
* #param args
* #throws SQLException
*/
public static void main(String[] args) throws SQLException {
try {
Class.forName(driverName);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(1);
}
//replace "hive" here with the name of the user the queries should run as
Connection con = DriverManager.getConnection("jdbc:hive2://localhost:10000/default", "cloudera", "cloudera");
//Connection con = DriverManager.getConnection("jdbc:hive2://");
Statement stmt = con.createStatement();
String tableName = "testHiveDriverTable";
stmt.execute("drop table if exists " + tableName);
stmt.execute("create table " + tableName + " (key int, value string)");
String sql = "show tables '" + tableName + "'";
System.out.println("Running: " + sql);
ResultSet res = stmt.executeQuery(sql);
if (res.next()) {
System.out.println(res.getString(1));
}
}
}
and my C program looks like this
#include<stdio.h>
#include "jni.h"
int main ( void )
{
char cpath;
JNIEnv *env;
JavaVM *jvm;
int res;
jclass cls;
jmethodID mid = NULL;
//JavaVMOption options;
JavaVMOption options [3];
options[0].optionString="-Djava.class.path=desired-classpath";
options[1].optionString = "-verbose:class";
options[2].optionString = "-Xdebug";
JavaVMInitArgs vm_args;
vm_args.version = JNI_VERSION_1_6;
vm_args.options = options;
vm_args.nOptions = 3;
res = JNI_CreateJavaVM (&jvm, (void **)&env, &vm_args);
if(res < 0 || !env)
printf("\nUnable to Launch JVM\n");
else
printf("**JVM launched successfully**\n");
cls = ( * env) -> FindClass(env, "HiveJdbcClient2");
printf("**cls**:\n",cls);
if (cls!=NULL)
printf("**HiveJdbcClient2 find success**\n");
else
printf("**Something happend with FindClass\n");
mid = (* env) -> GetStaticMethodID (env,cls, "main", "([Ljava/lang/String;)V");
if (mid!=0)
{
printf("**GetStaticMethodID success -test worked**\n");
(* env) -> CallStaticVoidMethod (env, cls, mid, NULL);
}
(* jvm) -> DestroyJavaVM (jvm);
return 0;
}
When I run just the java program, then the jdbc connection seems to to work. However, when invoked through the C program, the execution stops at DriverManager.getConnection() without any error messages or warning. I've checked that the hiverserver2 is running. Are there any additional configurations that need to be done like in hive-site.xml? I'm using cloudera CDH virtualbox so have not performed any additional configurations. I've seen a couple of similar queries and resolutions on this site but nothing has worked for me....

Answer 1

I resolved the issue by catching exceptions in the JNI calls. By way, the issue was missing classes which I corrected in -D.Java.path.