Merge pull request #1972 from josevalim/jv-nospawn_process

Introduce the no_spawn_compiler_process option

3 files changed, 17 insertions, 3 deletions

diff --git a/lib/compiler/doc/src/compile.xml b/lib/compiler/doc/src/compile.xml
index 1a71c83521..f64986d55c 100644
--- a/lib/compiler/doc/src/compile.xml
+++ b/lib/compiler/doc/src/compile.xml
@@ -415,6 +415,17 @@ module.beam: module.erl \
               is not documented, and can change between releases.</p>
           </item>
 
+          <tag><c>no_spawn_compiler_process</c></tag>
+          <item>
+            <p>By default, all code is compiled in a separate process
+              which is terminated at the end of compilation. However,
+              some tools, like Dialyzer or compilers for other BEAM languages,
+              may already manage their own worker processes and spawning
+              an extra process may slow the compilation down.
+              In such scenarios, you can pass this option to stop the
+              compiler from spawning an additional process.</p>
+          </item>
+
           <tag><c>no_strict_record_tests</c></tag>
           <item>
             <p>This option is not recommended.</p>
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index d894694c79..7a0531cb2b 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -210,8 +210,11 @@ do_compile(Input, Opts0) ->
                               {error,Reason}
                       end
              end,
-    %% Dialyzer has already spawned workers.
-    case lists:member(dialyzer, Opts) of
+    %% Some tools, like Dialyzer, has already spawned workers
+    %% and spawning extra workers actually slow the compilation
+    %% down instead of speeding it up, so we provide a mechanism
+    %% to bypass the compiler process.
+    case lists:member(no_spawn_compiler_process, Opts) of
         true ->
             IntFun();
         false ->
diff --git a/lib/dialyzer/src/dialyzer_utils.erl b/lib/dialyzer/src/dialyzer_utils.erl
index abd89034f3..ebe4040c34 100644
--- a/lib/dialyzer/src/dialyzer_utils.erl
+++ b/lib/dialyzer/src/dialyzer_utils.erl
@@ -643,7 +643,7 @@ sets_filter([Mod|Mods], ExpTypes) ->
 src_compiler_opts() ->
   [no_copt, to_core, binary, return_errors,
    no_inline, strict_record_tests, strict_record_updates,
-   dialyzer].
+   dialyzer, no_spawn_compiler_process].
 
 -spec format_errors([{module(), string()}]) -> [string()].