Apart from the fact that bubble 1 and 2 point to the wrong person.

The image makes perfect sense if you read it in the order 3, 1, 2.

OH!

I was assuming the joke was that 1 and 3 got swapped around. Because it doesn't really make sense for 2 to be mixed up, considering it's from a different person entirely...

Which meant that the joke just made no sense, because swapping 1 and 3 is just as nonsense as the original order.

🤦🏽‍♀️ Thanks for explaining, my brain must have corrected the race condition.

Regarding threads: I have had good experience with using thread safe queues everywhere to exchange data between threads, it's the right tool in many cases, but I doubt queues to be useful when coding for performance.

Half of the people posting here act like they are terrified of using threads. Then someone is explaining what a race condition is and they get 100+ upvotes like they just solved world hunger.

Why is there a duck in your programmerhumor

It doesn't violate any rules.. Imagine both the "speaker" and the "text" are being updated by separate threads. A program that would eventually display the behavior in this meme is simple, and I'm a bit embarrassed to have written it because of this comment:

#include <pthread.h>
#include <stdio.h>

char* speakers[] = {
    "Alice",
    "Bob"
};
int speaker = 0;

void* change_speaker(void* arg)
{
    (void)arg;

    for (;;) {
        speaker = speaker == 0 ? 1 : 0;
    }
}

char* texts[] = {
    "Hi Bob",
    "Hi Alice, what's up?",
    "Not much Bob",
};
int text = 0;

void* change_text(void* arg)
{
    (void)arg;
    for (;;) {
        switch (text) {
        case 0:
            text = 1;
            break;
        case 1:
            text = 2;
            break;
        case 2:
            text = 0;
            break;
        }
    }
}

int main(int argc, char* argv[])
{
    pthread_t speaker_swapper, text_swapper;

    pthread_create(&text_swapper, NULL, change_text, NULL);
    pthread_create(&speaker_swapper, NULL, change_speaker, NULL);
    for (int i = 0; i < 3; ++i) {
        printf("%s: %s\n", speakers[speaker], texts[text]);
    }
}

I don't see OP explaining it anywhere.

It's just threads running out of order.

Why are you all overengineering the joke this much?

Oh, I guess that makes sense. One person asks if the other is an expert, they reply they read the for dummies book, cue comically aggressive response.

There's so much going on in this exchange, including two separate jokes as well as weird multi-person race conditions, that I couldn't reverse engineer it.

Yes for example Python implements them using semaphores.