The first level of synchronization is on method scope:
public class HelloSync {
private Map dictionary = new HashMap();
public synchronized void boringDeveloper(String key, String value) {
long startTime = (new java.util.Date()).getTime();
value = value + "_"+startTime;
dictionary.put(key, value);
System.out.println("I did this in "+
((new java.util.Date()).getTime() - startTime)+" miliseconds");
}
}
However we should consider the basic rule of concurrency: Do not hold the lock longer than necessary.
An updated version is using synchronization in a specific block:
public class HelloSync {
private Map dictionary = new HashMap();
public void boringDeveloper(String key, String value) {
long startTime = (new java.util.Date()).getTime();
value = value + "_"+startTime;
synchronized (dictionary) {
dictionary.put(key, value);
}
System.out.println("I did this in "+
((new java.util.Date()).getTime() - startTime)+" miliseconds");
}
}
Related Article:
Reference: Reduce lock granularity – Concurrency optimization from our JCG partner Adrianos Dadis at Java, Integration and the virtues of source.
