Issue #20249 has been updated by osyoyu (Daisuke Aritomo). I've received feedback that if we switch the default, no one would really use the full output mode, so we shall keep the current behavior for better bug reports. I agree that Ruby users (non-CRuby/C ext developers) won't run into crashes often, and they probably won't mind the long output. So, my new proposal is the following: (1) Introduce a new environment variable `RUBY_CRASH_REPORT`. When set to `backtrace`, only the Ruby-level backtrace and C-level backtrace is printed. C extension developers (who don't want to compile their own Ruby with `RUBY_DEBUG=1`) would use this feature. (2) Default to `RUBY_CRASH_REPORT=minimal` behavior when `RUBY_DEBUG=1`. This feature is for CRuby core developers who don't want to configure an env var all the time. `RUBY_DEBUG` behavior is intentionally flipped from @byroot 's comment. I believe non-`RUBY_DEBUG` behavior should be consistent with what Ruby users see. ---------------------------------------- Feature #20249: Print only backtraces in rb_bug(), by default https://bugs.ruby-lang.org/issues/20249#change-106715 * Author: osyoyu (Daisuke Aritomo) * Status: Open * Priority: Normal ---------------------------------------- ## Background When a segfault or some unexpected situation occurs, `rb_bug()` is called and prints some few hundred to thousands of lines. The most helpful parts are (arguably) "Ruby level backtrace information" and "C-level backtrace information", but those parts are buried in the very lengthy report. In particular, the "Other runtime information" which contains the list of loaded features (scripts?) and the process memory map could be extremely long despite it does not come very useful, at least when developing C extensions. Even a minimal report from a simple script would consist of 250 lines and require 7 PgUps on my MacBook Air (13 inch) to reach the backtrace part, which contains all the information I need. ## Proposal My proposal is to default to a "minimal report" mode with a limited set of sections, perhaps only "Ruby level backtrace information" and "C level backtrace information" only When a full report is desired (i.e. for bug reports), the user could re-run the script with an special environment variable, such as `RUBY_FULL_CRASH_REPORT=1`. Rust implmements a similar pattern. It doesn't print the full backtrace on panics by default; instead, it guides the user to re-run the program with `RUST_BACKTRACE=1`. It might be hard to reproduce some crashes and segfaults, especially in long-running daemons. It might be nice to default to the "full" mode when stdout is not a tty, since daemons tend to run in non-tty environments. ## Appendix A typical crash report would look like this: ``` ../../example.rb: [BUG] ruby 3.4.0dev (2024-01-20T15:27:19Z master 366b14c0cd) [arm64-darwin23] -- Crash Report log information -------------------------------------------- (5 lines) -- Control frame information ----------------------------------------------- (~50 lines) -- Ruby level backtrace information ---------------------------------------- (depends on program; typically ~50 lines in Rails) -- C level backtrace information ------------------------------------------- (50+-ish lines, depends on program) -- Machine register context ------------------------------------------------ (~10 lines) -- Threading information --------------------------------------------------- (2 lines) -- Other runtime information ----------------------------------------------- * Loaded script (1 line) * Loaded features (depends on program; 800+ lines in Rails) * Process memory map (depends on environment; around 200 lines?) -- https://bugs.ruby-lang.org/