On 6/30/20 10:15 AM, Simen Kjærås wrote:
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.

Thanks.


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) {
         thread_joinAll();
     }
}


First, you can just use shared static dtor, as this runs once at the end of the program. At the very least, you can run the setting of mainTid in a shared constructor to avoid the race conditions (also no need to check if its set already).

Second, I realized, thread_joinAll is already being done by the runtime:

https://github.com/dlang/druntime/blob/67618bd2dc8905ad5dee95f3329109aebd839b74/src/rt/dmain2.d#L226

So the question really becomes -- why is it necessary to call thread_joinAll in main?

It's because the main thread's TLS static destructor is closing the owner mailbox, which is sending a message to all the threads that the owner is terminated, causing your threads to exit immediately.

See here: https://github.com/dlang/phobos/blob/268b56be494cc4f76da54a66a6960fa7e527c4ed/std/concurrency.d#L223

Honestly though, I think this is the correct behavior -- if you exit main, you are expecting the program to not hang indefinitely.

-Steve

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