[ruby-core:122261] [Ruby Bug#21368] Moving objects with finalizer between Ractors crashes

Issue #21368 has been reported by peterzhu2118 (Peter Zhu). ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` -- https://bugs.ruby-lang.org/

Issue #21368 has been updated by peterzhu2118 (Peter Zhu). Assignee set to ractor ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368#change-113405 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` -- https://bugs.ruby-lang.org/

Issue #21368 has been updated by zzak (zzak _). It seemed fun to patch, but I'm not sure this is correct: https://github.com/ruby/ruby/pull/13452 ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368#change-113454 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` -- https://bugs.ruby-lang.org/

Issue #21368 has been updated by osyoyu (Daisuke Aritomo). File 0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch added The script in the description didn't crash in my environments (the following). Explicitly calling `GC.start` did. - Linux `ruby 3.5.0dev (2025-05-28T04:34:40Z master d064fd067b) +PRISM [x86_64-linux]` - macOS `ruby 3.5.0dev (2025-05-28T04:34:40Z master d064fd067b) +PRISM [arm64-darwin24]` ```ruby r = Ractor.new do Ractor.receive # don't bind to a variable (let it be garbage collected) GC.start end o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) r.take ``` I have attached an updated version of @zzak_'s patch which resolves this crash, but I suppose this is inappropiate since this will leak outer variables in the following case: ```ruby r = Ractor.new do Ractor.receive GC.start # `unshareable` happens to get read in this Ractor end o = Object.new unshareable = +"hello" ObjectSpace.define_finalizer(o, proc { |id| p unshareable }) r.send(o, move: true) r.take ``` Maybe simply marking objects with a finalizer ineligible for moving is more appropiate. ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368#change-113475 * Author: peterzhu2118 (Peter Zhu) * Status: Assigned * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` ---Files-------------------------------- 0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch (883 Bytes) -- https://bugs.ruby-lang.org/

Issue #21368 has been updated by zzak (zzak _).
Maybe simply marking objects with a finalizer ineligible for moving is more appropiate.
Thanks for checking, I've updated the PR to raise if the object has a finalizer. I'm not sure if we should do the check in like `make_shareable_check_shareable` instead, for example. ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368#change-113684 * Author: peterzhu2118 (Peter Zhu) * Status: Assigned * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` ---Files-------------------------------- 0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch (883 Bytes) -- https://bugs.ruby-lang.org/

Issue #21368 has been updated by osyoyu (Daisuke Aritomo). Maybe this ticket should be merged with https://bugs.ruby-lang.org/issues/21315 ? ---------------------------------------- Bug #21368: Moving objects with finalizer between Ractors crashes https://bugs.ruby-lang.org/issues/21368#change-113737 * Author: peterzhu2118 (Peter Zhu) * Status: Assigned * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table. The following script crashes: ```ruby r = Ractor.new do loop { Ractor.receive } end 1_000.times do o = Object.new ObjectSpace.define_finalizer(o, proc { |id| }) r.send(o, move: true) end ``` ---Files-------------------------------- 0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch (883 Bytes) -- https://bugs.ruby-lang.org/
participants (3)
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osyoyu (Daisuke Aritomo)
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peterzhu2118 (Peter Zhu)
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zzak (zzak _)