Warn in verbose mode on defining a finalizer that captures the object #2264
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tenderlove
reviewed
Jul 2, 2019
| VALUE key = rb_obj_id(child); | ||
| if (rb_hash_has_key(data->set, key)) | ||
| return; | ||
| rb_hash_aset(data->set, key, Qtrue); |
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Should we just use the object itself as the hash key?
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When we use rb_objspace_reachable_objects_from we get internal objects - RUBY_T_IMEMO and I think specifically instruction sequences. These aren't hashable (don't respond to hash). I'd welcome a suggestion about alternative data structures to use instead of a Hash - could I use the st hash structure directly? Or some kind of identity hash?
tenderlove
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Jul 3, 2019
Various things can cause GC to occur when compaction is running, for
example resizing the object identity map:
```
frame #24: 0x000000010c784a10 ruby`gc_grey [inlined] push_mark_stack(stack=<unavailable>, data=<unavailable>) at gc.c:4311:42
frame #25: 0x000000010c7849ff ruby`gc_grey(objspace=0x00007fc56c804400, obj=140485906037400) at gc.c:4907
frame #26: 0x000000010c78f881 ruby`gc_start at gc.c:6464:8
frame #27: 0x000000010c78f5d1 ruby`gc_start [inlined] gc_marks_start(objspace=0x00007fc56c804400, full_mark=<unavailable>) at gc.c:6009
frame #28: 0x000000010c78f3c0 ruby`gc_start at gc.c:6291
frame #29: 0x000000010c78f399 ruby`gc_start(objspace=0x00007fc56c804400, reason=<unavailable>) at gc.c:7104
frame #30: 0x000000010c78930c ruby`objspace_xmalloc0 [inlined] objspace_malloc_fixup(objspace=<unavailable>, mem=0x000000011372a000, size=<unavailable>) at gc.c:9665:5
frame #31: 0x000000010c7892f5 ruby`objspace_xmalloc0(objspace=0x00007fc56c804400, size=12582912) at gc.c:9707
frame #32: 0x000000010c89bc13 ruby`st_init_table_with_size(type=<unavailable>, size=<unavailable>) at st.c:605:39
frame #33: 0x000000010c89c5e2 ruby`rebuild_table_if_necessary [inlined] rebuild_table(tab=0x00007fc56c40b250) at st.c:780:19
frame #34: 0x000000010c89c5ac ruby`rebuild_table_if_necessary(tab=0x00007fc56c40b250) at st.c:1142
frame #35: 0x000000010c89c379 ruby`st_insert(tab=0x00007fc56c40b250, key=140486132605040, value=140485922918920) at st.c:1161:5
frame #36: 0x000000010c794a16 ruby`gc_compact_heap [inlined] gc_move(objspace=0x00007fc56c804400, scan=<unavailable>, free=<unavailable>, moved_list=140485922918960) at gc.c:7441:9
frame #37: 0x000000010c794917 ruby`gc_compact_heap(objspace=0x00007fc56c804400, comparator=<unavailable>) at gc.c:7695
frame #38: 0x000000010c79410d ruby`gc_compact [inlined] gc_compact_after_gc(objspace=0x00007fc56c804400, use_toward_empty=1, use_double_pages=<unavailable>, use_verifier=1) at gc.c:0:22
```
We *definitely* need the heap to be in a consistent state during
compaction, so this commit sets the current state to "during_gc" so that
nothing will trigger a GC until the heap finishes compacting.
This fixes the bug we saw when running the tests for ruby#2264
matzbot
pushed a commit
that referenced
this pull request
Jul 3, 2019
Various things can cause GC to occur when compaction is running, for
example resizing the object identity map:
```
frame #24: 0x000000010c784a10 ruby`gc_grey [inlined] push_mark_stack(stack=<unavailable>, data=<unavailable>) at gc.c:4311:42
frame #25: 0x000000010c7849ff ruby`gc_grey(objspace=0x00007fc56c804400, obj=140485906037400) at gc.c:4907
frame #26: 0x000000010c78f881 ruby`gc_start at gc.c:6464:8
frame #27: 0x000000010c78f5d1 ruby`gc_start [inlined] gc_marks_start(objspace=0x00007fc56c804400, full_mark=<unavailable>) at gc.c:6009
frame #28: 0x000000010c78f3c0 ruby`gc_start at gc.c:6291
frame #29: 0x000000010c78f399 ruby`gc_start(objspace=0x00007fc56c804400, reason=<unavailable>) at gc.c:7104
frame #30: 0x000000010c78930c ruby`objspace_xmalloc0 [inlined] objspace_malloc_fixup(objspace=<unavailable>, mem=0x000000011372a000, size=<unavailable>) at gc.c:9665:5
frame #31: 0x000000010c7892f5 ruby`objspace_xmalloc0(objspace=0x00007fc56c804400, size=12582912) at gc.c:9707
frame #32: 0x000000010c89bc13 ruby`st_init_table_with_size(type=<unavailable>, size=<unavailable>) at st.c:605:39
frame #33: 0x000000010c89c5e2 ruby`rebuild_table_if_necessary [inlined] rebuild_table(tab=0x00007fc56c40b250) at st.c:780:19
frame #34: 0x000000010c89c5ac ruby`rebuild_table_if_necessary(tab=0x00007fc56c40b250) at st.c:1142
frame #35: 0x000000010c89c379 ruby`st_insert(tab=0x00007fc56c40b250, key=140486132605040, value=140485922918920) at st.c:1161:5
frame #36: 0x000000010c794a16 ruby`gc_compact_heap [inlined] gc_move(objspace=0x00007fc56c804400, scan=<unavailable>, free=<unavailable>, moved_list=140485922918960) at gc.c:7441:9
frame #37: 0x000000010c794917 ruby`gc_compact_heap(objspace=0x00007fc56c804400, comparator=<unavailable>) at gc.c:7695
frame #38: 0x000000010c79410d ruby`gc_compact [inlined] gc_compact_after_gc(objspace=0x00007fc56c804400, use_toward_empty=1, use_double_pages=<unavailable>, use_verifier=1) at gc.c:0:22
```
We *definitely* need the heap to be in a consistent state during
compaction, so this commit sets the current state to "during_gc" so that
nothing will trigger a GC until the heap finishes compacting.
This fixes the bug we saw when running the tests for #2264
eregon
pushed a commit
to ruby/spec
that referenced
this pull request
Jul 27, 2019
[Feature #15974] Closes: ruby/ruby#2264
headius
pushed a commit
to headius/spec
that referenced
this pull request
Oct 31, 2024
[Feature #15974] Closes: ruby/ruby#2264
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There's a really common mistake people make when using
define_finalizer- they capture the object in the finalizer.https://www.mikeperham.com/2010/02/24/the-trouble-with-ruby-finalizers/
This PR warns about that, when in verbose mode (it's too slow to do always.)