9- Strategies for Thread Safety

Jul 03, 2026 15:08 · 2:50 · English · Whisper Turbo · 3 דוברים

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We have a few strategies for writing thread safe code.

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That is code that can be safely executed across multiple threads.

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The simplest solution is not to share data across threads in the first

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place. This is called confinement because we want to confine or restrict

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each thread to have its own data.

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For example,

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instead of sharing a download status object across many download tasks,

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you could have each download task have its own download status object.

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When all these tasks are complete,

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we can combine the result.

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So this is the simplest strategy.

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I will show you how to do this in the next video.

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Another strategy is using immutable or unchangeable

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objects.

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An object is immutable if its state or data cannot be

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changed after it's created.

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For example,

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the string class in Java is immutable.

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If we convert a string to uppercase,

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we get a new string object.

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The original string object is not changed.

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So,

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sharing immutable objects between threads is totally fine because these

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threads can only read immutable objects.

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They cannot modify them.

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Another strategy is to prevent multiple threads from accessing

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the same object concurrently.

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This is called synchronization because we synchronize or coordinate the access

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to an object across different threads.

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We do that by using locks.

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So we put a lock on certain parts of our code and only one

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thread at a time can execute that part.

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Other threads have to wait.

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So synchronization forces the code to run sequentially,

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which is against the idea of concurrency.

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Plus,

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implementing synchronization is challenging and error prone.

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One of the problems we may run into is a deadlock which happens when two threads

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wait for each other indefinitely.

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So thread one waits for thread two and at the same time thread

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two waits for thread one.

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That's a deadlock and can cause our application to crash.

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So generally speaking synchronization is bad and you should avoid it

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as much as possible.

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Another strategy is to use atomic classes in Java like atomic integer.

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These classes allow us to achieve threat safety without using locks.

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So if we increment an atomic integer,

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the Java virtual machine will execute the increment operation as one

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single atomic operation.

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It's not going to break it down into three smaller operations.

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That's why they're called atomic.

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They're like atoms.

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They cannot be broken down.

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And finally,

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another strategy is partitioning data into segments that can be accessed

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concurrently.

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Java provides a number of collection classes that support concurrency using

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partitioning.

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So multiple threads can access a collection object,

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but only one thread at a time can access a segment in that collection.

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So these are five common strategies we have for writing thread safe code.

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Over the next few lessons,

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we're going to explore each of these strategies.

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