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@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.

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On 14-04-2012 18:04, Russel Winder wrote:
> 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@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.
>

http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_join.3.html#ERRORS

We can rule out these:

EDEADLK: Can't happen with your code.
EINVAL (second case): No other thread is trying to join.
ESRCH: Shouldn't happen since druntime registers threads with libpthread.

So, the first case of EINVAL (thread is not a joinable thread) must be the cause. I have no clue *why* though...

-- 
- Alex

On 04/14/2012 04:56 PM, Alex Rønne Petersen wrote:
> On 14-04-2012 18:04, Russel Winder wrote:
>> 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@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.
>>
>
> http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_join.3.html#ERRORS
>
>
> We can rule out these:
>
> EDEADLK: Can't happen with your code.
> EINVAL (second case): No other thread is trying to join.
> ESRCH: Shouldn't happen since druntime registers threads with libpthread.
>
> So, the first case of EINVAL (thread is not a joinable thread) must be
> the cause. I have no clue *why* though...
>
If you merge the two foreach loops into one, doing t.start();t.join(); it doesn't have this issue. Also, when I run your code repeatedly the number of successful numbers printed changes a lot.
I'm assuming that you're trying to join a thread that already exited...
-Matt

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@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.

On Sat, 2012-04-14 at 17:10 -0400, Matt Soucy wrote:
[...]
> If you merge the two foreach loops into one, doing t.start();t.join();
> it doesn't have this issue. Also, when I run your code repeatedly the
> number of successful numbers printed changes a lot.
> I'm assuming that you're trying to join a thread that already exited...

This matches with Artur's comment about laziness/strictness, but doing the above is only useful for experimentation, it cannot be a final solution since it enforces serialization of thread execution.

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Sat, 2012-04-14 at 23:27 +0200, Somedude wrote:
[...]
> 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.

Thanks for this, a useful alternative realization.

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder