16- Adders

Jul 03, 2026 22:41 · 2:09 · English · Whisper Turbo · 2 Đầu ghi

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Tập tin

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S… Speaker 2 (16- Adders)

So atomic objects are great for implementing counters,

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S… Speaker 2 (16- Adders)

but if you have multiple threads updating a value frequently,

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S… Speaker 2 (16- Adders)

it's better to use one of the other classes in Java.

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S… Speaker 2 (16- Adders)

They're faster than atomic types.

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S… Speaker 2 (16- Adders)

So we have long adder for adding long values

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S… Speaker 2 (16- Adders)

and double adder.

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S… Speaker 2 (16- Adders)

Let me show you how they work.

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S… Speaker 2 (16- Adders)

So we have the same code as before.

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S… Speaker 2 (16- Adders)

This is the code that has a race condition.

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S… Speaker 2 (16- Adders)

So when we run this program,

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S… Speaker 2 (16- Adders)

we see this weird number over here.

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S… Speaker 2 (16- Adders)

Let's solve this problem using an adder class.

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S… Speaker 1 (16- Adders)

So in the last video,

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S… Speaker 2 (16- Adders)

we replaced this integer field with an atomic adder.

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S… Speaker 2 (16- Adders)

Now we're going to replace this with a long adder.

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S… Speaker 2 (16- Adders)

And then we set this to a new long adder.

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S… Speaker 1 (16- Adders)

All right.

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S… Speaker 2 (16- Adders)

Now in our getter,

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S… Speaker 2 (16- Adders)

we call the int value method.

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S… Speaker 2 (16- Adders)

This will return the result as an integer.

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S… Speaker 2 (16- Adders)

We also have byte value,

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S… Speaker 1 (16- Adders)

short value,

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S… Speaker 1 (16- Adders)

double value,

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S… Speaker 1 (16- Adders)

and so on.

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S… Speaker 2 (16- Adders)

Internally, this long other object keeps an array of counters that can grow

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S… Speaker 1 (16- Adders)

on demand.

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S… Speaker 2 (16- Adders)

So we don't have a single place in memory where our value is stored.

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S… Speaker 2 (16- Adders)

We have a bunch of array cells each holding a counter value.

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S… Speaker 2 (16- Adders)

So different threads can modify this counter variables concurrently.

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S… Speaker 2 (16- Adders)

That's why these other classes are faster than atomic types because

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S… Speaker 1 (16- Adders)

they allow more throughput.

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S… Speaker 2 (16- Adders)

So here we can call

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S… Speaker 2 (16- Adders)

int value method but internally this method is going to call another

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S… Speaker 2 (16- Adders)

method called sum which is going to add up all these counter values

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S… Speaker 1 (16- Adders)

and return the result.

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S… Speaker 2 (16- Adders)

Now the int value will call this method and then convert the result to

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S… Speaker 1 (16- Adders)

an integer.

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S… Speaker 2 (16- Adders)

Now in our increment method we call increment.

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S… Speaker 2 (16- Adders)

We also have add for adding a long value.

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S… Speaker 2 (16- Adders)

We have decrement,

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S… Speaker 2 (16- Adders)

we have reset,

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S… Speaker 1 (16- Adders)

and so on.

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S… Speaker 2 (16- Adders)

So let's call the increment method.

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S… Speaker 1 (16- Adders)

That's all we had to do.

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S… Speaker 2 (16- Adders)

Let's run our program.

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S… Speaker 2 (16- Adders)

The race condition is gone.

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S… Speaker 2 (16- Adders)

So if you have multiple threads updating a value frequently,

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S… Speaker 2 (16- Adders)

prefer the adder classes to atomic types.

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