Thread join behaviour

[Somedude]

Le 14/04/2012 18:04, Russel Winder a écrit :
> I thought the following would terminate gracefully having printed 0..9
> in some (random) order:
> 
>         #! /usr/bin/env rdmd
>         
>         import std.algorithm ;
>         import std.range ;
>         import std.stdio ;
>         import core.thread ;
>         
>         int main ( immutable string[] args ) {
>           auto threads = map ! ( ( int a ) {
>               void delegate ( ) f ( ) {
>                 return delegate ( ) { writeln ( a ) ; } ; 
>               }
>               return new Thread ( f )  ;
>             } ) ( iota ( 10 ) ) ;
>           foreach ( t ; threads ) { t.start ( ) ; }
>           foreach ( t ; threads ) { t.join ( ) ; }
>           return 0 ;
>         }
> 
> However, this does not happen, at least with 2.059 on Linux as per
> Debian Unstable.  Instead I get:
> 
>         1
>         2
>         4
>         5
>         8
>         3
>         7
>         6
>         9
>         0
>         core.thread.ThreadException at src/core/thread.d(906): Unable to join thread
>         ----------------
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(_Dmain+0x83) [0x425edb]
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(extern (C) int rt.dmain2.main(int, char**).void runMain()+0x17) [0x429bab]
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(extern (C) int rt.dmain2.main(int, char**).void tryExec(scope void delegate())+0x23) [0x42952b]
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(extern (C) int rt.dmain2.main(int, char**).void runAll()+0x3d) [0x429bf9]
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(extern (C) int rt.dmain2.main(int, char**).void tryExec(scope void delegate())+0x23) [0x42952b]
>         /tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/initializingWithAMap.d.9532BBED12C814F25F173A9AEAB96D0D(main+0xd3) [0x4294c3]
>         /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xfd) [0x7f1ed17f8ead]
>         ----------------
> 
> I think I must be having a dumb moment as my reaction continues to be
> WTF.
> 

This works:

int main ( immutable string[] args ) {

  auto threadgroup = new ThreadGroup();

  void delegate ( ) f (int a ) {
    return delegate ( ) { writeln ( a ) ; } ;
  }

  for ( int n = 0; n < 10; n++ ) {
    threadgroup.create(f(n));
  }
  threadgroup.joinAll( );
  return 0 ;
}

Threads are tracked by the threadgroup, which knows who can be joined.