[pull] master from ruby:master#205
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pull[bot] merged 3 commits intoturkdevops:masterfrom Aug 26, 2025
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If we malloc when the current Ractor is locked, we can deadlock because
GC requires VM lock and Ractor barrier. If another Ractor is waiting on
this Ractor lock, then it will deadlock because the other Ractor will
never join the barrier.
For example, this script deadlocks:
r = Ractor.new do
loop do
Ractor::Port.new
end
end
100000.times do |i|
r.send(nil)
puts i
end
On debug builds, it fails with this assertion error:
vm_sync.c:75: Assertion Failed: vm_lock_enter:cr->sync.locked_by != rb_ractor_self(cr)
On non-debug builds, we can see that it deadlocks in the debugger:
Main Ractor:
frame #3: 0x000000010021fdc4 miniruby`rb_native_mutex_lock(lock=<unavailable>) at thread_pthread.c:115:14
frame #4: 0x0000000100193eb8 miniruby`ractor_send0 [inlined] ractor_lock(r=<unavailable>, file=<unavailable>, line=1180) at ractor.c:73:5
frame #5: 0x0000000100193eb0 miniruby`ractor_send0 [inlined] ractor_send_basket(ec=<unavailable>, rp=0x0000000131092840, b=0x000000011c63de80, raise_on_error=true) at ractor_sync.c:1180:5
frame #6: 0x0000000100193eac miniruby`ractor_send0(ec=<unavailable>, rp=0x0000000131092840, obj=4, move=<unavailable>, raise_on_error=true) at ractor_sync.c:1211:5
Second Ractor:
frame #2: 0x00000001002208d0 miniruby`rb_ractor_sched_barrier_start [inlined] rb_native_cond_wait(cond=<unavailable>, mutex=<unavailable>) at thread_pthread.c:221:13
frame #3: 0x00000001002208cc miniruby`rb_ractor_sched_barrier_start(vm=0x000000013180d600, cr=0x0000000131093460) at thread_pthread.c:1438:13
frame #4: 0x000000010028a328 miniruby`rb_vm_barrier at vm_sync.c:262:13 [artificial]
frame #5: 0x00000001000dfa6c miniruby`gc_start [inlined] rb_gc_vm_barrier at gc.c:179:5
frame #6: 0x00000001000dfa68 miniruby`gc_start [inlined] gc_enter(objspace=0x000000013180fc00, event=gc_enter_event_start, lock_lev=<unavailable>) at default.c:6636:9
frame #7: 0x00000001000dfa48 miniruby`gc_start(objspace=0x000000013180fc00, reason=<unavailable>) at default.c:6361:5
frame #8: 0x00000001000e3fd8 miniruby`objspace_malloc_increase_body [inlined] garbage_collect(objspace=0x000000013180fc00, reason=512) at default.c:6341:15
frame #9: 0x00000001000e3fa4 miniruby`objspace_malloc_increase_body [inlined] garbage_collect_with_gvl(objspace=0x000000013180fc00, reason=512) at default.c:6741:16
frame #10: 0x00000001000e3f88 miniruby`objspace_malloc_increase_body(objspace=0x000000013180fc00, mem=<unavailable>, new_size=<unavailable>, old_size=<unavailable>, type=<unavailable>) at default.c:8007:13
frame #11: 0x00000001000e3c44 miniruby`rb_gc_impl_malloc [inlined] objspace_malloc_fixup(objspace=0x000000013180fc00, mem=0x000000011c700000, size=12582912) at default.c:8085:5
frame #12: 0x00000001000e3c30 miniruby`rb_gc_impl_malloc(objspace_ptr=0x000000013180fc00, size=12582912) at default.c:8182:12
frame #13: 0x00000001000d4584 miniruby`ruby_xmalloc [inlined] ruby_xmalloc_body(size=<unavailable>) at gc.c:5128:12
frame #14: 0x00000001000d4568 miniruby`ruby_xmalloc(size=<unavailable>) at gc.c:5118:34
frame #15: 0x00000001001eb184 miniruby`rb_st_init_existing_table_with_size(tab=0x000000011c2b4b40, type=<unavailable>, size=<unavailable>) at st.c:559:39
frame #16: 0x00000001001ebc74 miniruby`rebuild_table_if_necessary [inlined] rb_st_init_table_with_size(type=0x00000001004f4a78, size=524287) at st.c:585:5
frame #17: 0x00000001001ebc5c miniruby`rebuild_table_if_necessary [inlined] rebuild_table(tab=0x000000013108e2f0) at st.c:753:19
frame #18: 0x00000001001ebbfc miniruby`rebuild_table_if_necessary(tab=0x000000013108e2f0) at st.c:1125:9
frame #19: 0x00000001001eba08 miniruby`rb_st_insert(tab=0x000000013108e2f0, key=262144, value=4767566624) at st.c:1143:5
frame #20: 0x0000000100194b84 miniruby`ractor_port_initialzie [inlined] ractor_add_port(r=0x0000000131093460, id=262144) at ractor_sync.c:399:9
frame #21: 0x0000000100194b58 miniruby`ractor_port_initialzie [inlined] ractor_port_init(rpv=4750065560, r=0x0000000131093460) at ractor_sync.c:87:5
frame #22: 0x0000000100194b34 miniruby`ractor_port_initialzie(self=4750065560) at ractor_sync.c:103:12
Migrate from expect-test to insta snapshot testing library. While expect-test is very small and has a limited surface, it does not handle nextest well; it while doing inline snapshot updates, it races other test processes to update the file, leading to frequent "Failed to process macro invocation" errors. insta handles this by doing batches; it writes to temporary files which can then be committed in a batch using `cargo insta review` or `INSTA_UPDATE=always`.
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