[ruby-core:113386] [Ruby master Feature#19627] Add a way to detect if the Ruby VM is running in C API
Issue #19627 has been reported by ianks (Ian Ker-Seymer). ---------------------------------------- Feature #19627: Add a way to detect if the Ruby VM is running in C API https://bugs.ruby-lang.org/issues/19627 * Author: ianks (Ian Ker-Seymer) * Status: Open * Priority: Normal ---------------------------------------- Currently, there is no supported way to check if the Ruby VM has been shut down. There are a couple of workarounds that I know of: 1. Setup an exit handler which sets a global variable (like I did in https://github.com/tmm1/stackprof/pull/200). 2. In Ruby 2.4 thru 3.2, you could check the hidden `ruby_vm_global_ptr != NULL`. For my use, in rb-sys there is a feature to automatically report Rust memory allocations via `rb_gc_adjust_memory_usage`. However, there is a bug that can cause processes to deadlock and/or segfault if a Rust destructor gets called after the VM quits (which can happen in Rust background threads). Currently, I don’t think there’s a way to safely make this feature work. (https://github.com/oxidize-rb/rb-sys/pull/205) It would be nice to have an official way to know if the Ruby VM is available, basically just a `ruby_current_vm_ptr != null`. Thoughts? -- https://bugs.ruby-lang.org/
Issue #19627 has been updated by mdalessio (Mike Dalessio). I reported a related issue in https://bugs.ruby-lang.org/issues/19580 which I fixed with https://github.com/ruby/ruby/pull/7663 Maybe you want to explore a similar fix which will short-circuit functions like `rb_gc_adjust_memory_usage` instead of forcing callers to figure out if it's safe? ---------------------------------------- Feature #19627: Add a way to detect if the Ruby VM is running in C API https://bugs.ruby-lang.org/issues/19627#change-102965 * Author: ianks (Ian Ker-Seymer) * Status: Open * Priority: Normal ---------------------------------------- Currently, there is no supported way to check if the Ruby VM has been shut down. There are a couple of workarounds that I know of: 1. Setup an exit handler which sets a global variable (like I did in https://github.com/tmm1/stackprof/pull/200). 2. In Ruby 2.4 thru 3.2, you could check the hidden `ruby_vm_global_ptr != NULL`. For my use, in rb-sys there is a feature to automatically report Rust memory allocations via `rb_gc_adjust_memory_usage`. However, there is a bug that can cause processes to deadlock and/or segfault if a Rust destructor gets called after the VM quits (which can happen in Rust background threads). Currently, I don’t think there’s a way to safely make this feature work. (https://github.com/oxidize-rb/rb-sys/pull/205) It would be nice to have an official way to know if the Ruby VM is available, basically just a `ruby_current_vm_ptr != null`. Thoughts? -- https://bugs.ruby-lang.org/
Issue #19627 has been updated by ianks (Ian Ker-Seymer). That’s a good idea. I’ll put a patch up for that. So far I’ve encountered this issue this issue in `rb_gc_adjust_memory_usage` and `rb_during_gc`, so I still think having the ability to check for a Ruby VM is important for writing robust code. At the very least, it would provide an escape hatch in case there are undiscovered edge cases lurking. ---------------------------------------- Feature #19627: Add a way to detect if the Ruby VM is running in C API https://bugs.ruby-lang.org/issues/19627#change-102968 * Author: ianks (Ian Ker-Seymer) * Status: Open * Priority: Normal ---------------------------------------- Currently, there is no supported way to check if the Ruby VM has been shut down. There are a couple of workarounds that I know of: 1. Setup an exit handler which sets a global variable (like I did in https://github.com/tmm1/stackprof/pull/200). 2. In Ruby 2.4 thru 3.2, you could check the hidden `ruby_vm_global_ptr != NULL`. For my use, in rb-sys there is a feature to automatically report Rust memory allocations via `rb_gc_adjust_memory_usage`. However, there is a bug that can cause processes to deadlock and/or segfault if a Rust destructor gets called after the VM quits (which can happen in Rust background threads). Currently, I don’t think there’s a way to safely make this feature work. (https://github.com/oxidize-rb/rb-sys/pull/205) It would be nice to have an official way to know if the Ruby VM is available, basically just a `ruby_current_vm_ptr != null`. Thoughts? -- https://bugs.ruby-lang.org/
Issue #19627 has been updated by ianks (Ian Ker-Seymer). For documentations sake, [he's a real world reproduction of this issue that happens when calling TLS destructors](https://github.com/bytecodealliance/wasmtime-rb/actions/runs/4850597226/jobs...). In Ruby < 3.3-dev, I'm able to avoid this by checking the hidden `ruby_current_vm_ptr` symbol so the code won't segfault after VM shutdown. ``` -- C level backtrace information ------------------------------------------- /home/runner/.rubies/ruby-head/lib/libruby.so.3.3(rb_print_backtrace+0xd) [0x7f360aab3a3f] /home/runner/work/ruby-dev-builder/ruby-dev-builder/vm_dump.c:785 /home/runner/.rubies/ruby-head/lib/libruby.so.3.3(rb_vm_bugreport) /home/runner/work/ruby-dev-builder/ruby-dev-builder/vm_dump.c:1101 /home/runner/.rubies/ruby-head/lib/libruby.so.3.3(rb_bug_for_fatal_signal+0xf4) [0x7f360a8b8c94] /home/runner/work/ruby-dev-builder/ruby-dev-builder/error.c:814 /home/runner/.rubies/ruby-head/lib/libruby.so.3.3(sigsegv+0x4d) [0x7f360a9feecd] /home/runner/work/ruby-dev-builder/ruby-dev-builder/signal.c:964 /lib/x86_64-linux-gnu/libc.so.6(0x7f360a413520) [0x7f360a413520] /home/runner/.rubies/ruby-head/lib/libruby.so.3.3(rb_gc_adjust_memory_usage+0xe) [0x7f360a8dedbe] /home/runner/work/ruby-dev-builder/ruby-dev-builder/gc.c:12743 /lib/x86_64-linux-gnu/libc.so.6(__call_tls_dtors+0x3f) [0x7f360a416d9f] /lib/x86_64-linux-gnu/libc.so.6(0x7f360a4165c9) [0x7f360a4165c9] /lib/x86_64-linux-gnu/libc.so.6(on_exit+0x20) [0x7f360a416610] /lib/x86_64-linux-gnu/libc.so.6(0x7f360a3fad97) [0x7f360a3fad97] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7f360a3fae40] [0x55e16aa391d5] ``` ---------------------------------------- Feature #19627: Add a way to detect if the Ruby VM is running in C API https://bugs.ruby-lang.org/issues/19627#change-102969 * Author: ianks (Ian Ker-Seymer) * Status: Open * Priority: Normal ---------------------------------------- Currently, there is no supported way to check if the Ruby VM has been shut down. There are a couple of workarounds that I know of: 1. Setup an exit handler which sets a global variable (like I did in https://github.com/tmm1/stackprof/pull/200). 2. In Ruby 2.4 thru 3.2, you could check the hidden `ruby_vm_global_ptr != NULL`. For my use, in rb-sys there is a feature to automatically report Rust memory allocations via `rb_gc_adjust_memory_usage`. However, there is a bug that can cause processes to deadlock and/or segfault if a Rust destructor gets called after the VM quits (which can happen in Rust background threads). Currently, I don’t think there’s a way to safely make this feature work. (https://github.com/oxidize-rb/rb-sys/pull/205) It would be nice to have an official way to know if the Ruby VM is available, basically just a `ruby_current_vm_ptr != null`. Thoughts? -- https://bugs.ruby-lang.org/
participants (2)
-
ianks (Ian Ker-Seymer) -
mdalessio (Mike Dalessio)