On Tuesday, 30 June 2020 at 13:44:38 UTC, aberba wrote:
On Tuesday, 30 June 2020 at 12:48:32 UTC, Simen Kjærås wrote:
On Tuesday, 30 June 2020 at 08:15:54 UTC, aberba wrote:
On Tuesday, 30 June 2020 at 00:33:41 UTC, Ali Çehreli wrote:
On 6/29/20 4:34 PM, aberba wrote:

> So with this, without the Thread.sleep() to block main from
exiting, the
> spawned thread  will terminate immediately.

You can call core.thread.thread_joinAll at the end of main.
So I tried that initially but my (){ writeln(...) } wasn't printing anything in console. Could that be related to stdout buffering? The program kept running though.

So I guess the error is elsewhere, but I'm not sure where and how.

Yeah, you're right. I changed receiveTimeout() to receive() to try something and forgot to change it back.

Jeez, I hate myself.


So how can I now hide the core.thread.thread_joinAll so the library user doesn't have to type it themselves in main() ? I don't see how that can be done.

__gshared Tid mainTid;
static this() {
    if (mainTid.tupleof[0] is null) {
        mainTid = thisTid;
static ~this() {
    if (thisTid == mainTid) {

The above code does the trick.

So, what does it do? __gshared means 'this variable is accessible to all threads'. static this() runs upon creation of any thread including the main thread. Since the main thread will run first*, it gets to store its Tid in mainTid, and every other thread will see a populated mainTid and leave it alone. In the module destructor, which runs after main(), we call thread_joinAll() iff we're the main thread.

Now, why should you not do this? Well first, instead of getting a tidy crash you get a process that doesn't end. Second, there's the race conditions described below. Third, there's the principle of least astonishment. D programmers expect that when main() returns, the program will exit shortly(ish), while this zombie could continue running indefinitely.


*I'm pretty sure this is possibly wrong, if a module constructor spawns a new thread. There's also a possible race condition where newly spawned modules may conceivably not see a properly initialized mainTid.

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