Hi,
1, My servlet is not in the singleThread mode.
2, The db.insert(or db.upgrade) are external class which handle the database
access. it is a separated class, I wrote a test case for it and they all working
fine.
3. I isolated assignNum() method from the servlet into a standard class. Then I
created a test program to generated 50 threads which each of them is gonna to
call the assingNum() method. At first I didn't apply the static to the method.
It turned out that all the threads return the same number after calling the
assignNum(). After I added the static, all threads return unique number which is
what I wanted.
Because of the complexity of the database access code, I didn't post the code.
Here is the test code to create multiple threads to call the assignNum() method:
public class MultipleThreadsTest {
public static void main (String[] args) {
for (int i = 0; i < 50; i++){
new SimpleThread(String.valueOf(i)).start();
}
}
}
public class SimpleThread extends Thread {
public SimpleThread(String str) {
super(str);
}
public void run() {
for (int i = 0; i < 50; i++) {
Number numberObj = new Number();
System.out.println(Number.assignNum("test", "1111", "TT", "cmt none"));
try {
sleep((long)(Math.random() * 1000));
} catch (InterruptedException e) {}
}
System.out.println("DONE! " + getName());
}
}
public class Number{
public static synchronized String assignNum(String name, String uID,
String requestType, String
comment){
String rID = "";
//DBaccess is the database access class. It used Oracle SID to make the
connection and insert, update the table.
DBaccess db = new DBaccess();
rID = db.DBinsert(name, uID, requestType, comment);
db.updateSeqNum(requestType);
return rID;
}
}
Thanks for all the replies.
Tiana
On Thu, 5 Oct 2000 11:48:45 -0500, Milt Epstein <[EMAIL PROTECTED]> wrote:
>On Thu, 5 Oct 2000, Tiana Zhang wrote:
>
>> The reason I think I have to put static keyword for the method is
>> because my method is going to update the database by JDBC
>> connection. I don't want multiple thread updating the database at
>> the same time.
>
>static should have nothing to do with this. static just controls
>whether something is a class variable/method or an instance
>variable/method. (If you don't understand the difference, you should
>get a basic Java book.)
>
>
>> Here is my code:
>>
>> public static synchronized String assignNum(String name, String uID, String
>> requestType, String comment){
>>
>> String rID = "";
>> try{
>> rID = db.DBinsert(name, uID, requestType, comment);
>> db.updateSeqNum(requestType);
>>
>> } catch (Exception e) {
>> System.err.println(e.toString());
>> }
>> return rID;
>> }
>
>There's lots of information missing here. Like what is db? What do
>its methods do? How is assignNum called? And do you have your
>servlet implementing SingleThreadModel? There may be other relevant
>considerations as well.
>
>Milt Epstein
>Research Programmer
>Software/Systems Development Group
>Computing and Communications Services Office (CCSO)
>University of Illinois at Urbana-Champaign (UIUC)
>[EMAIL PROTECTED]
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