writeln() sometimes double prints from main() if I run a thread checking for input?

[Ivan Kazmenko via Digitalmars-d-learn]

On Wednesday, 30 August 2017 at 13:24:55 UTC, Ivan Kazmenko wrote:
> On Wednesday, 30 August 2017 at 10:55:20 UTC, Timothy Foster 
> wrote:
>> import std.stdio, core.thread;
>>
>> void main(){	
>> 	auto thread = new Thread(&func).start;
>>         writeln("Output");
>> 	writeln("Output2");
>> 	writeln("Output3");
>> 	while(true){}
>> }
>>
>> void func(){
>>     foreach(line; stdin.byLineCopy){}
>> }
>
> I also cannot reproduce this.
>
> My current system is Win7 64-bit.  I tried 32-bit dmd 2.072.0 
> and 2.075.1, with optimizations turned on and off, but it 
> prints correctly tens of times in each case.
>
> Try running the program in a bare console (cmd.exe on Windows, 
> or some *sh on Linux).  If the problem goes away, your usual 
> environment is likely at fault.  If not,.. well, no idea for 
> now.

Hey, I followed my own advice and do see the same issue! when:
1. compiling with dmd 2.075.1 (optimization switches seem to be 
irrelevant but the issue does not reproduce with 2.072.0),
2. running in a bare cmd.exe, and
3. running the program as just "a.exe", so that it waits for 
console input (previously I redirected some input to it, like 
"a.exe <a.exe" or "a.exe <a.d", and the issue does not reproduce 
then).
Interesting.  As to what to do with it, no idea for now.  At the 
very least we can issue a bug report, now that at least two 
people can reproduce it, so it is unlikely to be 
environment-dependent.

Ivan Kazmenko.