Check for NULL fields in TYPEDDATA memsize functions#15633
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luke-gru merged 1 commit intoruby:masterfrom Dec 18, 2025
Merged
Check for NULL fields in TYPEDDATA memsize functions#15633luke-gru merged 1 commit intoruby:masterfrom
luke-gru merged 1 commit intoruby:masterfrom
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Some TYPEDDATA objects allocate struct fields using the GC right after they get created, and in that case the VM can try to perform a GC and join a barrier if another ractor started one. If we're dumping the heap in another ractor, this acquires a barrier and it will call the `rb_obj_memsize` function on this object. We can't assume these struct fields are non-null. This also goes for C extensions, which may cause problems with heap dumping from a ractor if their memsize functions aren't coded correctly to check for NULL fields. Because dumping the heap from a ractor is likely a rare scenario and it has only recently been introduced, we'll have to see how this works in practice and if it causes bugs.
byroot
approved these changes
Dec 18, 2025
jhawthorn
approved these changes
Dec 18, 2025
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Some TYPEDDATA objects allocate struct fields using the GC right after they get created, and in that case the VM can try to perform a GC and join a barrier if another ractor started one. If we're dumping the heap in another ractor, this acquires a barrier and it will call the
rb_obj_memsizefunction on this object. We can't assume these struct fields are non-null. This also goes for C extensions, which may cause problems with heap dumping from a ractor if their memsize functions aren't coded correctly to check for NULL fields. Because dumping the heap from a ractor is likely a rare scenario and it has only recently been introduced, we'll have to see how this works in practice and if it causes bugs.