'jdb' - The Java Debugger

Part:   1  2  3  4  5  6  7  8   9 

(Continued from previous part...)

What I have done here:

• I used "next" again. The sub thread jumped over the calculation loop between line 33 and 36. This is correct, since "current" has "3", a prime number, no need to do any calculation.
• Then I used "next" and "print" several times. I saw prime number 3 was correctly recorded in the "primes" array.

4. Going back to the main thread:

Thread-0[1] stop at PrimeNumberSeeker:19
Set breakpoint PrimeNumberSeeker:19
Thread-0[1] cont
>
Breakpoint hit: "thread=main", PrimeNumberSeeker.main(), line=19 bci=25
19             System.out.println( i+", "+t.current+", "+t.count);

main[1] where all
main:
  [1] PrimeNumberSeeker.main (PrimeNumberSeeker.java:19)
Thread-0:
  [1] java.lang.Thread.sleep (native method)
  [2] PrimeNumberSeeker.run (PrimeNumberSeeker.java:42)

main[1] print i
 i = 11

main[1] print t.current
 t.current = 3

main[1] print t.count
 t.count = 1

What I have done here:

• I created another breakpoint in the main thread at line 19.
• Then I allowed both threads to run naturally to the next breakpoint, line 19. The command prompt is changed back to "main[1]".
• Then I used "where all" to check where the execution are stopped in all threads. It is interesting to see that the sub thread stopped inside the sleep() method.
• Then I checked some local variables, "i", "t.current", and "t.count". Their values were all correct.

5. Switching threads:

main[1] cont
>
Breakpoint hit: "thread=main", PrimeNumberSeeker.main(), line=19 bci=25
19             System.out.println( i+", "+t.current+", "+t.count);

main[1] print t.current
 t.current = 14

main[1] print t.count
 t.count = 6

main[1] where all
...
main:
  [1] PrimeNumberSeeker.main (PrimeNumberSeeker.java:19)
Thread-0:
  [1] java.lang.Thread.sleep (native method)
  [2] PrimeNumberSeeker.run (PrimeNumberSeeker.java:42)

main[1] threads
...
Group main:
  (java.lang.Thread)0x1         main          running
  (PrimeNumberSeeker)0x118      Thread-0      running (at breakpoint)

main[1] thread 280

Thread-0[1] list
Current method is native

Thread-0[1] step out
11, 22, 8
>
Step completed: "thread=Thread-0", PrimeNumberSeeker.run(), line=45
45             }

Thread-0[1] list
41             try {
42                sleep(delay);
43             } catch (InterruptedException e) {
44                System.out.println("Runner interrupted.");
45 =>          }
46          }
47       }
48    }

Thread-0[1] print count
 count = 8

(Continued on next part...)

Part:   1  2  3  4  5  6  7  8   9