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<v Instructor>Hi, welcome back.</v>

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In this video, I just wanted to tell you

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a little bit about killing threads.

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I've gone back here in the code to the code before

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using the ThreadPoolExecutor,

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and notice that we've got thread1.start

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and thread2.start.

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Then we've got space to write more code,

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and then we wait for them to finish.

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Inside this space here, you could write some code

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to kill the thread, for example, if it meets some criteria

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or maybe you no longer need it or something.

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You could write some code to kill the thread,

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but you should not do that.

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Don't kill a thread. Wait for it to finish.

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If you kill a thread manually without being really careful,

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what can happen is that your thread has acquired the GIL,

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you kill it before it releases the GIL,

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and then what you've got is the GIL is gone.

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No other thread can pick it up

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because it wasn't released before.

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Threads will not release the resources

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just by killing them.

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You need to release the resources manually

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in the thread code itself.

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If you have your thread and it's started,

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and it's using the GIL and then you kill it,

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the GIL is gone, no other thread can get the GIL,

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your Python programme will stop.

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It won't terminate, because the thread here

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will be waiting to finish,

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but it won't be able to do anything,

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and if that happens, if you have a resource

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that's being used and nothing else can use it,

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this is called a deadlock in computing,

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and it's a bad thing.

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So, just be careful. Don't kill threads.

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And that's just all I say.

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Don't kill threads, it's not easy to do,

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and I don't recommend it.

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If you kill threads, you're going to have problems,

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so don't do it.

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That's it for this video. I'll see you in the next one.