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Listing 1.2:
import java.util.*;
import java.text.NumberFormat;
class Synch
{
private static long[ ] locking_time = new long[100];
private static long[ ] not_locking_time = new long[100];
private static final long ITERATIONS = 10000000;
synchronized long locking (long a, long b){return a + b;}
long not_locking (long a, long b){return a + b;}
private void test( int id )
{
long start = System.currentTimeMillis();
for(long i = ITERATIONS; --i >= 0 ;)
{ locking(i,i);
}
locking_time[id] = System.currentTimeMillis() - start;
start = System.currentTimeMillis();
for(long i = ITERATIONS; --i >= 0 ;)
{ not_locking(i,i);
}
not_locking_time[id] = System.currentTimeMillis() - start;
}
static void print_results( int id )
{
NumberFormat compositor = NumberFormat.getInstance();
compositor.setMaximumFractionDigits( 2 );
double time_in_synchronization = locking_time[id] - not_locking_time[id];
System.out.println( "Pass " + id + ": Time lost: "
+ compositor.format( time_in_synchronization )
+ " ms. "
+ compositor.format( ((double)locking_time[id]/not_locking_time[id])*100.0 )
+ "% increase"
);
}
static public void main(String[ ] args) throws InterruptedException
{
final Synch tester = new Synch();
tester.test(0); print_results(0);
tester.test(1); print_results(1);
tester.test(2); print_results(2);
tester.test(3); print_results(3);
tester.test(4); print_results(4);
tester.test(5); print_results(5);
tester.test(6); print_results(6);
final Object start_gate = new Object();
Thread t1 = new Thread()
{ public void run()
{ try{ synchronized(start_gate) { start_gate.wait(); } }
catch( InterruptedException e ){}
tester.test(7);
}
};
Thread t2 = new Thread()
{ public void run()
{ try{ synchronized(start_gate) { start_gate.wait(); } }
catch( InterruptedException e ){}
tester.test(8);
}
};
Thread.currentThread().setPriority( Thread.MIN_PRIORITY );
t1.start();
t2.start();
synchronized(start_gate){ start_gate.notifyAll(); }
t1.join();
t2.join();
print_results( 7 );
print_results( 8 );
}
} | 
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