Functionality for disabling garbage collection

Being able to disable garbage collection over context
switches vastly simplifies implementation of yielding
native code that builds large or complex data structures
on the heap. This since the heap can be left in an
inconsistent state over the context switch.

1 files changed, 68 insertions, 11 deletions

diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index e66c6f09b6..bf31655066 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -55,7 +55,9 @@
 	 no_priority_inversion/1,
 	 no_priority_inversion2/1,
 	 system_task_blast/1,
-	 system_task_on_suspended/1]).
+	 system_task_on_suspended/1,
+	 gc_request_when_gc_disabled/1,
+	 gc_request_blast_when_gc_disabled/1]).
 -export([prio_server/2, prio_client/2]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
@@ -95,7 +97,8 @@ groups() ->
        otp_7738_resume]},
      {system_task, [],
       [no_priority_inversion, no_priority_inversion2,
-       system_task_blast, system_task_on_suspended]}].
+       system_task_blast, system_task_on_suspended,
+       gc_request_when_gc_disabled, gc_request_blast_when_gc_disabled]}].
 
 init_per_suite(Config) ->
     A0 = case application:start(sasl) of
@@ -2361,15 +2364,69 @@ system_task_on_suspended(Config) when is_list(Config) ->
 	    ok
     end.
 
-gc_req(_Pid, 0) ->
-    [];
-gc_req(Pid, N) ->
-    R0 = erts_internal:request_system_task(Pid, low, garbage_collect),
-    R1 = erts_internal:request_system_task(Pid, normal, garbage_collect),
-    R2 = erts_internal:request_system_task(Pid, high, garbage_collect),
-    R3 = erts_internal:request_system_task(Pid, max, garbage_collect),
-    [R0, R1, R2, R3 | gc_req(Pid, N-1)].
-		  
+gc_request_when_gc_disabled(Config) when is_list(Config) ->
+    Master = self(),
+    AIS = erts_debug:set_internal_state(available_internal_state, true),
+    {P, M} = spawn_opt(fun () ->
+			       true = erts_debug:set_internal_state(gc_state,
+								    false),
+			       Master ! {self(), gc_state, false},
+			       receive after 1000 -> ok end,
+			       Master ! {self(), gc_state, true},
+			       false = erts_debug:set_internal_state(gc_state,
+								     true),
+			       receive after 100 -> ok end
+		       end, [monitor, link]),
+    receive {P, gc_state, false} -> ok end,
+    ReqId = make_ref(),
+    async = garbage_collect(P, [{async, ReqId}]),
+    receive
+	{garbage_collect, ReqId, Result} ->
+	    ?t:fail({unexpected_gc, Result});
+	{P, gc_state, true} ->
+	    ok
+    end,
+    receive {garbage_collect, ReqId, true} -> ok end,
+    erts_debug:set_internal_state(available_internal_state, AIS),
+    receive {'DOWN', M, process, P, _Reason} -> ok end,
+    ok.
+
+gc_request_blast_when_gc_disabled(Config) when is_list(Config) ->
+    Master = self(),
+    AIS = erts_debug:set_internal_state(available_internal_state, true),
+    {P, M} = spawn_opt(fun () ->
+			       true = erts_debug:set_internal_state(gc_state,
+								    false),
+			       Master ! {self(), gc_state, false},
+			       receive after 1000 -> ok end,
+			       false = erts_debug:set_internal_state(gc_state,
+								     true),
+			       receive after 100 -> ok end
+		       end, [monitor, link]),
+    receive {P, gc_state, false} -> ok end,
+    PMs = lists:map(fun (N) ->
+			    Prio = case N rem 4 of
+				       0 -> max;
+				       1 -> high;
+				       2 -> normal;
+				       3 -> low
+				   end,
+			    spawn_opt(fun () ->
+					      erlang:garbage_collect(P)
+				      end, [monitor, link, {priority, Prio}])
+		    end, lists:seq(1, 10000)),
+    lists:foreach(fun ({Proc, Mon}) ->
+			  receive
+			      {'DOWN', Mon, process, Proc, normal} ->
+				  ok
+			  end
+		  end,
+		  PMs),
+    erts_debug:set_internal_state(available_internal_state, AIS),
+    receive {'DOWN', M, process, P, _Reason} -> ok end,
+    ok.
+
+
 %% Internal functions
 
 wait_until(Fun) ->