From 7f82eddfaa3b89f734b4d58f1de92db86e5880cf Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Tue, 19 Oct 2010 13:43:13 +0200 Subject: 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. --- erts/preloaded/ebin/init.beam | Bin 44348 -> 44504 bytes erts/preloaded/src/init.erl | 41 ++++++++++++++++++++++------------------- 2 files changed, 22 insertions(+), 19 deletions(-) (limited to 'erts/preloaded') diff --git a/erts/preloaded/ebin/init.beam b/erts/preloaded/ebin/init.beam index f1b54b7fcb..f8af88b899 100644 Binary files a/erts/preloaded/ebin/init.beam and b/erts/preloaded/ebin/init.beam differ diff --git a/erts/preloaded/src/init.erl b/erts/preloaded/src/init.erl index 3b98b9cddc..255f33c299 100644 --- a/erts/preloaded/src/init.erl +++ b/erts/preloaded/src/init.erl @@ -51,6 +51,9 @@ get_status/0,boot/1,get_arguments/0,get_plain_arguments/0, get_argument/1,script_id/0]). +%% for the on_load functionality; not for general use +-export([run_on_load_handlers/0]). + %% internal exports -export([fetch_loaded/0,ensure_loaded/1,make_permanent/2, notify_when_started/1,wait_until_started/0, @@ -308,24 +311,6 @@ boot_loop(BootPid, State) -> {stop,Reason} -> stop(Reason,State); {From,fetch_loaded} -> %% Fetch and reset initially loaded modules. - case whereis(?ON_LOAD_HANDLER) of - undefined -> - %% There is no on_load handler process, - %% probably because init:restart/0 has been - %% called and it is not the first time we - %% pass through here. - ok; - Pid when is_pid(Pid) -> - Pid ! run_on_load, - receive - {'EXIT',Pid,on_load_done} -> - ok; - {'EXIT',Pid,Res} -> - %% Failure to run an on_load handler. - %% This is fatal during start-up. - exit(Res) - end - end, From ! {init,State#state.loaded}, garb_boot_loop(BootPid,State#state{loaded = []}); {From,{ensure_loaded,Module}} -> @@ -1335,9 +1320,27 @@ archive_extension() -> %%% Support for handling of on_load functions. %%% +run_on_load_handlers() -> + Ref = monitor(process, ?ON_LOAD_HANDLER), + catch ?ON_LOAD_HANDLER ! run_on_load, + receive + {'DOWN',Ref,process,_,noproc} -> + %% There is no on_load handler process, + %% probably because init:restart/0 has been + %% called and it is not the first time we + %% pass through here. + ok; + {'DOWN',Ref,process,_,on_load_done} -> + ok; + {'DOWN',Ref,process,_,Res} -> + %% Failure to run an on_load handler. + %% This is fatal during start-up. + exit(Res) + end. + start_on_load_handler_process() -> register(?ON_LOAD_HANDLER, - spawn_link(fun on_load_handler_init/0)). + spawn(fun on_load_handler_init/0)). on_load_handler_init() -> on_load_loop([]). -- cgit v1.2.3 From d20bbf4f3fe70ed3a00990b0ceb11292732318b8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 20 Oct 2010 13:51:06 +0200 Subject: Teach -init_debug to print info about on_load handlers begin run --- erts/preloaded/ebin/init.beam | Bin 44504 -> 44856 bytes erts/preloaded/src/init.erl | 23 +++++++++++++++-------- 2 files changed, 15 insertions(+), 8 deletions(-) (limited to 'erts/preloaded') diff --git a/erts/preloaded/ebin/init.beam b/erts/preloaded/ebin/init.beam index f8af88b899..c8d3b78b35 100644 Binary files a/erts/preloaded/ebin/init.beam and b/erts/preloaded/ebin/init.beam differ diff --git a/erts/preloaded/src/init.erl b/erts/preloaded/src/init.erl index 255f33c299..3ab9a1cd6d 100644 --- a/erts/preloaded/src/init.erl +++ b/erts/preloaded/src/init.erl @@ -721,6 +721,7 @@ do_boot(Init,Flags,Start) -> BootList = get_boot(BootFile,Root), LoadMode = b2a(get_flag('-mode',Flags,false)), Deb = b2a(get_flag('-init_debug',Flags,false)), + catch ?ON_LOAD_HANDLER ! {init_debug_flag,Deb}, BootVars = get_flag_args('-boot_var',Flags), ParallelLoad = (Pgm =:= "efile") and (erlang:system_info(thread_pool_size) > 0), @@ -1343,18 +1344,21 @@ start_on_load_handler_process() -> spawn(fun on_load_handler_init/0)). on_load_handler_init() -> - on_load_loop([]). + on_load_loop([], false). -on_load_loop(Mods) -> +on_load_loop(Mods, Debug0) -> receive + {init_debug_flag,Debug} -> + on_load_loop(Mods, Debug); {loaded,Mod} -> - on_load_loop([Mod|Mods]); + on_load_loop([Mod|Mods], Debug0); run_on_load -> - run_on_load_handlers(Mods), + run_on_load_handlers(Mods, Debug0), exit(on_load_done) end. -run_on_load_handlers([M|Ms]) -> +run_on_load_handlers([M|Ms], Debug) -> + debug(Debug, {running_on_load_handler,M}), Fun = fun() -> Res = erlang:call_on_load_function(M), exit(Res) @@ -1366,9 +1370,12 @@ run_on_load_handlers([M|Ms]) -> erlang:finish_after_on_load(M, Keep), case Keep of false -> - exit({on_load_function_failed,M}); + Error = {on_load_function_failed,M}, + debug(Debug, Error), + exit(Error); true -> - run_on_load_handlers(Ms) + debug(Debug, {on_load_handler_returned_ok,M}), + run_on_load_handlers(Ms, Debug) end end; -run_on_load_handlers([]) -> ok. +run_on_load_handlers([], _) -> ok. -- cgit v1.2.3