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Race condition between VIO_update_in_place and the garbage collector #8986

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Race condition between VIO_update_in_place and the garbage collector #8986

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5990654
lock the record header before fetching its backversion with delta
AlexeyMochalov Apr 14, 2026
4ebd3ff
Changed according to Vlad Khorsun suggestion
AlexeyMochalov Apr 15, 2026
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14 changes: 7 additions & 7 deletions src/jrd/vio.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7321,16 +7321,17 @@ void VIO_update_in_place(thread_db* tdbb,

AutoTempRecord gc_rec;

if (!DPM_get(tdbb, org_rpb, LCK_write))
BUGCHECK(186); // msg 186 record disappeared

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@hvlad hvlad Apr 14, 2026

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Your change makes possible that two pages will be locked at the same time, this is not good.
When one have primary record version locked and need to get seconary version, he should call DPM_fetch_back().
Of course, after VIO_data(), primary record should be re-acquired again.

record_param temp2;
const Record* prior = org_rpb->rpb_prior;
if (prior)
{
temp2 = *org_rpb;
temp2.rpb_record = gc_rec = relation->getGCRecord(tdbb);
temp2.rpb_page = org_rpb->rpb_b_page;
temp2.rpb_line = org_rpb->rpb_b_line;

if (!DPM_fetch(tdbb, &temp2, LCK_read))
if (!DPM_fetch_back(tdbb, &temp2, LCK_read, -1))
BUGCHECK(291); // msg 291 cannot find record back version

VIO_data(tdbb, &temp2, relation->rel_pool);
Expand All @@ -7340,15 +7341,14 @@ void VIO_update_in_place(thread_db* tdbb,
if (temp2.rpb_prior)
temp2.rpb_flags |= rpb_delta;

temp2.rpb_number = org_rpb->rpb_number;
DPM_store(tdbb, &temp2, *stack, DPM_secondary);

const USHORT pageSpaceID = temp2.getWindow(tdbb).win_page.getPageSpaceID();
stack->push(PageNumber(pageSpaceID, temp2.rpb_page));
}

if (!DPM_get(tdbb, org_rpb, LCK_write))
BUGCHECK(186); // msg 186 record disappeared
if (!DPM_get(tdbb, org_rpb, LCK_write))
BUGCHECK(186); // msg 186 record disappeared
}

if (prior)
{
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