From 8a318a5e83d61f4533c72d82039cd4fc595cce3c Mon Sep 17 00:00:00 2001
From: pmoura <pmoura@b08c6af1-5177-4d33-ba66-4b1c6b8b522a>
Date: Mon, 31 Mar 2008 16:26:31 +0000
Subject: [PATCH] Updated the implementation of the thread_detach/1 predicate
 to help ensure that threads already terminated at the time of the call are
 destroyed instead of becoming zombie threads.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@2173 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
---
 pl/threads.yap | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/pl/threads.yap b/pl/threads.yap
index 2fe6677ec..fa71bf61e 100644
--- a/pl/threads.yap
+++ b/pl/threads.yap
@@ -147,18 +147,18 @@ thread_create(Goal, OutId, Options) :-
 
 '$thread_option'(Option, _, _, _, _, _, _, G0) :- var(Option), !,
 	'$do_error'(instantiation_error,G0).
+'$thread_option'(alias(Alias), Alias, _, _, _, _, _, G0) :- !,
+	( \+ atom(Alias) -> '$do_error'(type_error(atom,Alias),G0) ; true ).
 '$thread_option'(stack(Stack), _, Stack, _, _, _, _, G0) :- !,
 	( \+ integer(Stack) -> '$do_error'(type_error(integer,Stack),G0) ; true ).
 '$thread_option'(trail(Trail), _, _, Trail, _, _, _, G0) :- !,
 	( \+ integer(Trail) -> '$do_error'(type_error(integer,Trail),G0) ; true ).
 '$thread_option'(system(System), _, _, _, System, _, _, G0) :- !,
 	( \+ integer(System) -> '$do_error'(type_error(integer,System),G0) ; true ).
-'$thread_option'(alias(Alias), Alias, _, _, _, _, _, G0) :- !,
-	( \+ atom(Alias) -> '$do_error'(type_error(atom,Alias),G0) ; true ).
 '$thread_option'(detached(Detached), _, _, _, _, Detached, _, G0) :- !,
-	( Detached \== true, Detached \== false  -> '$do_error'(domain_error(thread_option,Detached+[true,false]),G0) ; true ).
+	( Detached \== true, Detached \== false -> '$do_error'(domain_error(thread_option,Detached+[true,false]),G0) ; true ).
 '$thread_option'(at_exit(AtExit), _, _, _, _, _, AtExit, G0) :- !,
-	( \+ callable(AtExit)  -> '$do_error'(type_error(callable,AtExit),G0) ; true ).
+	( \+ callable(AtExit) -> '$do_error'(type_error(callable,AtExit),G0) ; true ).
 '$thread_option'(Option, _, _, _, _, _, _, G0) :-
 	'$do_error'(domain_error(thread_option,Option),G0).
 
@@ -314,6 +314,11 @@ thread_detach(Id) :-
 	 fail
 	;
 	'$detach_thread'(Id0)
+	),
+	(	recorded('$thread_exit_status', [Id0|_], _) ->
+		'$erase_thread_info'(Id0),
+		'$thread_destroy'(Id0)
+	;	true
 	).
 
 thread_exit(Term) :-
@@ -324,7 +329,6 @@ thread_exit(Term) :-
 
 '$run_at_thread_exit'(Id0) :-
 	recorded('$thread_at_exit',[Id0|AtExit],R), erase(R),
-	writeq(at_exit-AtExit), nl,
 	'$thread_top_goal'(AtExit),
 	fail.
 '$run_at_thread_exit'(Id0) :-