erts: Make depth of current_stacktrace configurable

The BIF process_info(Pid, current_stacktrace) truncates the
stacktrace. The old behavior was to truncate long stacktraces to max
8 items. And this was hard coded. Now it is truncated to the value of
system_flag(backtrace_depth) instead. The backtrace_depth defaults to
8, but is configurable.

1 files changed, 11 insertions, 0 deletions

diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 0f999e0efe..2289cbabc7 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -437,11 +437,22 @@ t_process_info(Config) when is_list(Config) ->
     verify_loc(Line2, Res2),
     pi_stacktrace([{?MODULE,t_process_info,1,?LINE}]),
 
+    verify_stacktrace_depth(),
+
     Gleader = group_leader(),
     {group_leader, Gleader} = process_info(self(), group_leader),
     {'EXIT',{badarg,_Info}} = (catch process_info('not_a_pid')),
     ok.
 
+verify_stacktrace_depth() ->
+    CS = current_stacktrace,
+    OldDepth = erlang:system_flag(backtrace_depth, 0),
+    {CS,[]} = erlang:process_info(self(), CS),
+    _ = erlang:system_flag(backtrace_depth, 8),
+    {CS,[{?MODULE,verify_stacktrace_depth,0,_},_|_]} =
+        erlang:process_info(self(), CS),
+    _ = erlang:system_flag(backtrace_depth, OldDepth).
+
 pi_stacktrace(Expected0) ->
     {Line,Res} = {?LINE,erlang:process_info(self(), current_stacktrace)},
     {current_stacktrace,Stack} = Res,