fix: LMDB deadlock in resize detection during concurrent transaction begin#84
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R0BC0D3R wants to merge 1 commit into
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fix: LMDB deadlock in resize detection during concurrent transaction begin#84R0BC0D3R wants to merge 1 commit into
R0BC0D3R wants to merge 1 commit into
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…begin lmdb_resized() called wait_no_active_txns() without accounting for the active transaction held by the calling thread, causing a spin-wait deadlock when MDB_MAP_RESIZED was returned from lmdb_txn_begin(). Fix by temporarily decrementing num_active_txns before the wait and re-incrementing after, so the calling thread's own txn is excluded from the active count. lmdb_txn_renew() passes isactive=0 since it does not increment the counter. Ported from monero-project/monero PR #7958.
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ngeojiajun
approved these changes
May 16, 2026
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Summary
lmdb_txn_begin()triggered whenMDB_MAP_RESIZEDis returned during concurrent database accesslmdb_resized()calledwait_no_active_txns()without accounting forthe active transaction held by the calling thread, causing it to spin
forever waiting for a count that could never reach zero
isactiveflag from call sites so the calling thread's owntransaction is temporarily excluded from the active count during the wait