Столкновение с проблемой в потоке ⇐ JAVA

[Anonymous]

Я вызываю потоки на основе записей, выбранных из базы данных.
Однако я вижу, что одни и те же записи инициируются в потоке несколько раз.
Также я вставляю записи в пары ключ-значение внутри класса Mytask а затем повторяя его, чтобы обновить ответ обратно в базу данных. обновление ответа также не происходит для некоторых записей.
Фрагмент кода
try {

con = DriverManager.getConnection(url, user, password);
System.out.println("Database connected successfully" + "| | | | | |");
Statement UpdateStmt = con.createStatement();
Statement stmt = con.createStatement();
String sqlQuery = "select distinct a, b,C, D from IBL_PAYMENT_STG_TBL WHERE RESPONSEFLAG in ('N','P') and TO_CHAR(creationdate, 'DD-MM-YYYY') in (TO_CHAR(sysdate-1, 'DD-MM-YYYY'),TO_CHAR(sysdate, 'DD-MM-YYYY'))";
String sqlQuery2 = "select count(*) ct from IBL_PAYMENT_STG_TBL WHERE RESPONSEFLAG in ('N','P') and TO_CHAR(creationdate, 'DD-MM-YYYY') in (TO_CHAR(sysdate-1, 'DD-MM-YYYY'),TO_CHAR(sysdate, 'DD-MM-YYYY'))";
String sqlQuery3 = null;

ResultSet resultSet2 = stmt.executeQuery(sqlQuery2);
while (resultSet2.next()) {
cnt = resultSet2.getInt("ct");
countRecords = resultSet2.getInt("ct");
System.out.println("Total Number of records: " + cnt + "| | | | |");
}
resultSet2.close();
if (cnt > 0) {
System.out.println("Starting");
}
int op = 0;
int LoopCount = (int) Math.ceil((double) cnt / 15);
try {
for (int j = 0; j < LoopCount; j++) {
// keyValuePairs.clear();

if (cnt >= 15) {
op = 15;
} else {
op = cnt;
}

cnt = cnt - 15;
// Thread[] threads = new Thread[op]; //Array code
List threads = Collections.synchronizedList(new ArrayList()); //List code
ResultSet resultSet = stmt.executeQuery(sqlQuery);

int i = 0;
long J = 0;
String K;
String L;
String M;

while (resultSet.next() && i < op) {
// System.out.println("Thread Batch Started");
J = resultSet.getLong("a");
K = resultSet.getString("b");
L = resultSet.getString("D");
M = resultSet.getString("C");
// System.out.println(J + " : I " + i);
sqlQuery3 = "UPDATE IBL_PAYMENT_STG_TBL SET RESPONSEFLAG = 'IP' WHERE a = " + J;
UpdateStmt.executeQuery(sqlQuery3);
Thread thread = new Thread(new MyTask(J, K, L, keyValuePairs, M)); //List Code
thread.start(); //List Code
threads.add(thread); //List Code
// threads = new Thread(new MyTask(J, K, L, keyValuePairs, M,i)); //Array code
// threads.start(); // Array Code
i++;
}
// System.out.println("Threading Complete");
resultSet.close();

//code for list
synchronized (threads){
for (Thread thread: threads){
try {
thread.join();
}catch (Exception e){
e.printStackTrace();
}
}
}
//Code for Array
// try {
// for (Thread thread : threads) {
// thread.join(); // Wait for each thread to finish
// }
//// System.out.println("Thread Joined");
// } catch (Exception e) {
// e.printStackTrace();
// System.out.println("Thread Execution failed");
// }
}
} catch (Exception exception) {
exception.printStackTrace();
String ExceptionString = exception.toString();
System.out.println(ExceptionString);
} finally {

// Code to be executed after all threads have finished
System.out.println("ALL threads executed, Update starting");

for (Long ID : keyValuePairs.keySet()) {
try {
Statement Updatestmt = con.createStatement();

String opPayload = keyValuePairs.get(ID);
System.out.println("update statement: " + opPayload);
try {

// System.out.println("update statement: "+opPayload);
Updatestmt.executeQuery(opPayload);
System.out.println("Update successful for ID: " + ID);
} catch (Exception e) {
e.printStackTrace();
String ExceptionString = e.toString();
String query = "UPDATE IBL_PAYMENT_STG_TBL " +
" SET ERRORFLAG = 'Y' ," +
" RESPONSEFLAG = 'IP'" + "," +
" ATTRIBUTE3 = ' Update Error: " + ExceptionString + "'" + "," +
" ATTRIBUTE4 = '" + opPayload.replaceAll("'", " ") + "'" +
" WHERE a =" + ID;
System.out.println(ID + "|" + "update statement Exception: " + query + "| | | | |");
Updatestmt.executeQuery(query);
}

} catch (Exception e) {
e.printStackTrace();
String ExceptionString = e.toString();
System.out.println(ID + "|" + ExceptionString);
}
}
// con.commit(); cannot manually commit as auto commit is set true
con.close();
System.out.println("update done" + "| | | | | |");
}
} catch (SQLException throwables) {
throwables.printStackTrace();
System.out.println(throwables.toString());

} catch (Exception e) {
e.printStackTrace();
System.out.println(e.toString());
}


Подробнее здесь: https://stackoverflow.com/questions/786 ... -threading