Issue #21539 has been updated by Eregon (Benoit Daloze). For clarity, it's also fine if these symbols get renamed/changed/etc, exporting them doesn't imply any future compatibility, it's just best-effort. Without the export it's very difficult and hacky to get to them, which translates to cases that simply don't work based on how Ruby was installed (e.g. stripped or not). ---------------------------------------- Feature #21539: Export symbols for external profiling of stripped shared Ruby builds https://bugs.ruby-lang.org/issues/21539#change-119527 * Author: dalehamel (Dale Hamel) * Status: Open ---------------------------------------- ## Motivation External profilers such as [OpenTelemetry's eBPF profiler](https://github.com/open-telemetry/opentelemetry-ebpf-profiler) collect Ruby stacks from outside the Ruby process. Distribution packages commonly ship shared libruby but strip the full symbol table (`.symtab`) and debug information. Some of the symbols needed to discover Ruby's execution state are currently local symbols, so they disappear when stripped. Public dynamic symbols in `.dynsym` survive normal stripping. I'd like to narrow this proposal to making the necessary discovery symbols available in these stripped shared builds. ## Proposed exports Please export these three existing symbols from shared libruby: | Symbol | Purpose | | --- | --- | | `ruby_current_ec` | Locate the sampled native thread's execution context through TLS, providing access to its Ruby stack. | | `rb_vm_exec` | Identify the function's address range, where native stack unwinding should hand off to Ruby stack unwinding. The profiler does not call this function. | | `ruby_global_symbols` | Resolve Ruby method IDs to names for methods implemented in C. Stack walking can work without this, but those method names become `<unknown cfunc>`. | The profiler also needs `ruby_version`, which is already exported and requires no change. The requested outcome is that these symbols are available through `.dynsym` in installed shared builds, without requiring distributions to retain the full symbol table or users to install debug information just to locate them. ## Scope This is a symbol-visibility request, not a request for a general out-of-process profiling API: - No requirement to stabilize internal struct layouts or make these internals a supported C-extension API. - No additional profiling stack, per-frame bookkeeping, or in-process profiling machinery. - The profiler remains responsible for supporting version-specific layouts and interpreter/JIT behavior. This would address the symbol-discovery obstacle for stripped distribution builds without taking on the broader API design discussed in #19119. Related profiler discussion: https://github.com/open-telemetry/opentelemetry-ebpf-profiler/issues/202 -- https://bugs.ruby-lang.org/