Multi line tty printing weirdness from the non main thread

When working with Julia, it is not uncommon to encounter strange printing behavior, especially when dealing with multi-threading. One such issue is when the output from a non-main thread appears to be printed in a weird manner on the terminal. In this article, we will explore three different ways to solve this problem.

Solution 1: Using the `@sync` Macro

One way to address the issue of weird printing from non-main threads is by using the `@sync` macro. This macro ensures that all the tasks spawned within it are completed before moving on to the next line of code. By wrapping the code that prints the output in the `@sync` macro, we can ensure that the printing is done in the correct order.


@sync begin
    # Code that spawns non-main threads
    Threads.@spawn println("Hello from non-main thread 1")
    Threads.@spawn println("Hello from non-main thread 2")
    Threads.@spawn println("Hello from non-main thread 3")
end

Solution 2: Using `@threads` Macro

Another way to solve the weird printing issue is by using the `@threads` macro. This macro allows for parallel execution of code across multiple threads. By wrapping the code that prints the output in the `@threads` macro, we can ensure that the printing is done in the correct order.


@threads for i in 1:3
    println("Hello from non-main thread $i")
end

Solution 3: Using `@distributed` Macro

The third solution involves using the `@distributed` macro, which allows for distributed computing across multiple processes. By wrapping the code that prints the output in the `@distributed` macro, we can ensure that the printing is done in the correct order.


@distributed for i in 1:3
    println("Hello from non-main thread $i")
end

After exploring these three solutions, it is clear that the best option depends on the specific use case. If the goal is to ensure sequential execution of code, Solution 1 using the `@sync` macro is the most appropriate. However, if parallel execution is desired, either Solution 2 using the `@threads` macro or Solution 3 using the `@distributed` macro can be used. It is important to consider the specific requirements and limitations of the project before deciding on the best solution.

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