I have a list of files to download, and I want to download them in parallel. At the end of each of those parallel download I want to send the main thread a message from the parallel loop.

import std.concurrency, std.parallelism;

string[] files = ["a", "b", "c"];

void download(string[] links)
{
	auto owner = ownerTid();
	foreach (link; links.parallel())
	{
		// something
		owner.send(false);
	}
	owner.send(true);
}

void main()
{
	// I do not want my main thread to freeze
	spawn(&download, files);
	bool done = false;
	while (!done)
		receive((bool isDone) { done = isDone; });
}

But the compiler says:
Error: static assert:  "Aliases to mutable thread-local data not allowed."
source/app.d(19,7):        instantiated from here: spawn!(void function(string[]), string[])

How should I go around this? I think the parallel block is being restricted from sending messages to the owner.
Here,

std.concurrency is for noninteractive appications, the approach with gui timer was the correct one.

On Saturday, 27 June 2020 at 07:31:56 UTC, Kagamin wrote:
> std.concurrency is for noninteractive appications, the approach with gui timer was the correct one.

Thank you. That works but my progress bar is sometimes getting stuck because of a possible data race.
See https://forum.dlang.org/post/gacweulvbyorksetidcj@forum.dlang.org

Today I discovered Glib Idle so I was trying that out.

On Saturday, 27 June 2020 at 07:51:21 UTC, adnan338 wrote:
> On Saturday, 27 June 2020 at 07:31:56 UTC, Kagamin wrote:
>> std.concurrency is for noninteractive appications, the approach with gui timer was the correct one.
>
> Thank you. That works but my progress bar is sometimes getting stuck because of a possible data race.
> See https://forum.dlang.org/post/gacweulvbyorksetidcj@forum.dlang.org

Sometimes? In that code you write the progress variable only once, so it doesn't change after that. Nothing else can possibly happen there with or without multithreading.