Fix hang in on_load handlers in embedded mode

In embedded mode, all on_load handlers will be called after
loading all modules but before starting any servers. Therefore,
if an on_load handler calls any function in the code module that
calls the code server (such as code:priv_dir/1), there will be a
deadlock because the code server has not yet been started.

Fix this problem by invoking the on_load handlers after
having started most servers in the kernel application.

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/kernel/src/kernel.erl b/lib/kernel/src/kernel.erl
index 92ee7b441a..d3b0f6c712 100644
--- a/lib/kernel/src/kernel.erl
+++ b/lib/kernel/src/kernel.erl
@@ -143,6 +143,13 @@ init(safe) ->
     Boot = start_boot_server(),
     DiskLog = start_disk_log(),
     Pg2 = start_pg2(),
+
+    %% Run the on_load handlers for all modules that have been
+    %% loaded so far. Running them at this point means that
+    %% on_load handlers can safely call kernel processes
+    %% (and in particular call code:priv_dir/1 or code:lib_dir/1).
+    init:run_on_load_handlers(),
+
     {ok, {SupFlags, Boot ++ DiskLog ++ Pg2}}.
 
 get_code_args() ->