Synchronized {blocks} are not synchronized ?

Question

Hi
I have a stored procedure containing a method with a synchronized block :
public class MyClass {
private static Connection conn;
public static void insert(String stringData) {
synchronized (conn) {
//LOGGING
Date startTime = new java.util.Date();
... some code ...
//LOGGING
Date stopTime = new java.util.Date();
}I suppose that when a lot of concurrent users wil use the stored procedure, the synchronized block of code will not be executed at the same time. But when I do that my log dates are overcrossing, that means concurrent execution.
How can I make this code really synchronized ??
thanks,
Xavier
null

Answer 1

radiatejava wrote:
You mentioned there could be some thread caching - can you pls explain why/how ? Since the threads are not accessing the variable directly and instead they are querying the object using a method, why would the method return some old value ? I understand in case of direct access to the variable, a thread can cache the variable. Do you mean to say that threads will also cache the methods ? Otherwise, how is it possible to return the stale value. I am not expecting a blind answer like XClass is not thread safe (I too agree to this) but some explanation on how caching is being done with method calls too.You are thinking of it in a wrong way. It doesn't matter if methods are cached or not, methods are just static code blocks. The important thing to understand is that all data can be cached unless it is volatile or synchronized. The integer "inside" XClass is data, and that data might get cached, so e.g. getVar can return the cached value. It doesn't need to read the value from main memory. The same applies to setVar, it doesn't need to update the value in main memory.