Postpone deletion of modules to avoid code server bottleneck

Author: josevalim

lib/elixir/src/elixir_code_server.erl

@@ -69,8 +69,9 @@ handle_call(retrieve_compiler_module, _From, Config) ->
 
 handle_call(purge_compiler_modules, _From, Config) ->
   {Used, Unused, Counter} = Config#elixir_code_server.mod_pool,
-  _ = [code:purge(Module) || Module <- Used],
-  ModPool = {[], Used ++ Unused, Counter},
+  purge_used(Used),
+  Mods = lists:map(fun({Mod, _}) -> Mod end, Used),
+  ModPool = {[], Mods ++ Unused, Counter},
   {reply, {ok, length(Used)}, Config#elixir_code_server{mod_pool=ModPool}};
 
 handle_call(Request, _From, Config) ->
@@ -95,9 +96,9 @@ handle_cast({unrequire_files, Files}, Config) ->
   Unrequired = maps:without(Files, Current),
   {noreply, Config#elixir_code_server{required=Unrequired}};
 
-handle_cast({return_compiler_module, Module}, Config) ->
+handle_cast({return_compiler_module, Module, Purgeable}, Config) ->
   {Used, Unused, Counter} = Config#elixir_code_server.mod_pool,
-  ModPool = {[Module | Used], Unused, Counter},
+  ModPool = {[{Module, Purgeable} | Used], Unused, Counter},
   {noreply, Config#elixir_code_server{mod_pool=ModPool}};
 
 handle_cast(purge_compiler_modules, Config) ->
@@ -111,11 +112,9 @@ handle_cast(purge_compiler_modules, Config) ->
       %% purge them asynchronously, especially because they can
       %% block the code server. Ideally we would purge them in
       %% batches, but that's not supported at the moment.
-      Opts = [{monitor, [{tag, {purged, Used}}]}],
-      erlang:spawn_opt(fun() ->
-        [code:purge(Module) || Module <- Used],
-        ok
-      end, Opts)
+      Mods = lists:map(fun({Mod, _}) -> Mod end, Used),
+      Opts = [{monitor, [{tag, {purged, Mods}}]}],
+      erlang:spawn_opt(fun() -> purge_used(Used) end, Opts)
   end,
 
   ModPool = {[], Unused, Counter},
@@ -144,6 +143,13 @@ code_change(_Old, Config, _Extra) ->
 compiler_module(I) ->
   list_to_atom("elixir_compiler_" ++ integer_to_list(I)).
 
+purge_used(Used) ->
+  [begin
+    code:delete(Module),
+    Purgeable andalso code:purge(Module)
+  end || {Module, Purgeable} <- Used],
+  ok.
+
 defmodule(Pid, Tuple, #elixir_code_server{mod_ets=ModEts} = Config) ->
   ets:insert(elixir_modules, Tuple),
   Ref = erlang:monitor(process, Pid),

lib/elixir/src/elixir_compiler.erl

@@ -79,8 +79,7 @@ do_is_purgeable(<<_:4/binary, Size:32, Beam/binary>>) ->
 
 dispatch(Module, Fun, Args, Purgeable) ->
   Res = Module:Fun(Args),
-  code:delete(Module),
-  Purgeable andalso return_compiler_module(Module),
+  return_compiler_module(Module, Purgeable),
   Res.
 
 code_fun(nil) -> '__FILE__';
@@ -105,8 +104,8 @@ code_mod(Fun, Expr, Line, File, Module, Vars) when is_binary(File), is_integer(L
 retrieve_compiler_module() ->
   elixir_code_server:call(retrieve_compiler_module).
 
-return_compiler_module(Module) ->
-  elixir_code_server:cast({return_compiler_module, Module}).
+return_compiler_module(Module, Purgeable) ->
+  elixir_code_server:cast({return_compiler_module, Module, Purgeable}).
 
 allows_fast_compilation({'__block__', _, Exprs}) ->
   lists:all(fun allows_fast_compilation/1, Exprs);

lib/elixir/test/elixir/code_test.exs

@@ -803,23 +803,6 @@ defmodule Code.SyncTest do
     refute to_charlist(path) in :code.get_path()
   end
 
-  test "purges compiler modules" do
-    quoted = quote(do: :ok)
-    Code.compile_quoted(quoted)
-
-    {:ok, claimed} = Code.purge_compiler_modules()
-    assert claimed > 0
-
-    {:ok, claimed} = Code.purge_compiler_modules()
-    assert claimed == 0
-
-    quoted = quote(do: Agent.start_link(fn -> :ok end))
-    Code.compile_quoted(quoted)
-
-    {:ok, claimed} = Code.purge_compiler_modules()
-    assert claimed == 0
-  end
-
   test "returns previous options when setting compiler options" do
     Code.compiler_options(debug_info: false)
     assert Code.compiler_options(debug_info: true) == %{debug_info: false}
@@ -843,4 +826,15 @@ defmodule Code.SyncTest do
     :code.purge(CompileSample)
     :code.delete(CompileSample)
   end
+
+  test "purges compiler modules" do
+    quoted = quote(do: :ok)
+    Code.compile_quoted(quoted)
+
+    {:ok, claimed} = Code.purge_compiler_modules()
+    assert claimed > 0
+
+    {:ok, claimed} = Code.purge_compiler_modules()
+    assert claimed == 0
+  end
 end