Archive for December, 2004

Biaxin For Sale

Biaxin For Sale, Today, my friend ask me to review some code of him, his code will encounter some unexpected error. Online buy Biaxin without a prescription, He's very confused and worried. After digging into the code, online Biaxin without a prescription, Buy no prescription Biaxin online, I found the problem.


Here's the code slice :


private boolean done;
private Message[] messages;
... .., Biaxin overnight. Where can i find Biaxin online, synchronized(this) {
if(!done || messages ==null) {
// 1
try {
wait();
// 2
} catch (InterruptedException e) {
e.printStackTrace();
}

...

dispatchMessage(messages);

// 3

.., Biaxin For Sale.
}

dispatchMessage(Message[] messages) {
int length = messages.length;

// 4

.., Biaxin images. Purchase Biaxin, ...

messages = null;
}



When the program run, Biaxin from canada, Biaxin natural, it will throw NullPointerException sometimes, though very infrequent, online buying Biaxin. Biaxin class, And just because of its infrequence, it's hard to debug, australia, uk, us, usa. Biaxin For Sale, But when go through this code slice, I think Java Expert can learn where's the problem. Cheap Biaxin no rx, Try to imagine such scenario:


1) messages is null


2) Thread 1 check the condition in position 1 and waiting in position 2, and it will release the lock, buy Biaxin no prescription, Effects of Biaxin, So other thread can obtain it;


3) Thread 2 check the condition in position 1 and waiting in position 2 too;


4) When we get the message and notify all threads using notifyAll(), both thread 1 and thread 2 will be awaked but only one thread will obtain the lock.


5) Assume thread 1 will get the lock, no prescription Biaxin online, Buy Biaxin without prescription, and it will dispatch the message using dispatchMessage. after dispatching the message, buying Biaxin online over the counter, Rx free Biaxin, it unreference the messages.


6) When thread 1 finished dispatching the message and release the lock, low dose Biaxin. Biaxin used for, Thread 2 will obtain the lock, however, buy Biaxin without a prescription, Biaxin for sale, NOW, messages is null, Biaxin photos, Biaxin treatment, so it will throw NPE.


Then, how to solve the problem, Biaxin For Sale. Yeah, Biaxin no prescription, Purchase Biaxin for sale, it should use spin lock here. So, Biaxin no rx, Online buying Biaxin hcl, it will re-check the condition after being awaked and will avoid such problem.
That is, herbal Biaxin, Purchase Biaxin online, it should be



while(!done || message ==null)
... .., buy generic Biaxin. Order Biaxin online overnight delivery no prescription,

And this trick is called spin lock(reference1) , you can see detail discussion in this book (practice 54), my Biaxin experience. Biaxin blogs, BTW: You also can find this trick in "Effective Java", in item 50 - "Never use wait out of loop". And, this two book is really good and worth reading. :-)


Reference:


1) "Pratical Java" - Peter Haggar


2) "Effective Java" - Joshua Bloch

.

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