Fix deadlock when fetching next chunk#242
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staticlibs merged 1 commit intoduckdb:mainfrom Jun 2, 2025
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When connection is being closed, it closes all statements and all result sets on these statements. All this is done while holding connection lock. When fetching next chunk, result set needs to take both result set and connection locks. Because of the wrong order of taking these locks, concurrent `close()` call on result set, initiated from `Connection#close()` was causing a deadlock. This change reorders locks in `ResultSet#fetchChunk()` to fix this. Testing: new test added that reproduces the deadlock reliably (may need to raise the number of iterations). Fixes: duckdb#241
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This is a backport of the PR duckdb#242 to `v1.3-ossivalis` stable branch. When connection is being closed, it closes all statements and all result sets on these statements. All this is done while holding connection lock. When fetching next chunk, result set needs to take both result set and connection locks. Because of the wrong order of taking these locks, concurrent `close()` call on result set, initiated from `Connection#close()` was causing a deadlock. This change reorders locks in `ResultSet#fetchChunk()` to fix this. Testing: new test added that reproduces the deadlock reliably (may need to raise the number of iterations). Fixes: duckdb#241
staticlibs
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Jun 15, 2025
This is a backport of the PR #242 to `v1.3-ossivalis` stable branch. When connection is being closed, it closes all statements and all result sets on these statements. All this is done while holding connection lock. When fetching next chunk, result set needs to take both result set and connection locks. Because of the wrong order of taking these locks, concurrent `close()` call on result set, initiated from `Connection#close()` was causing a deadlock. This change reorders locks in `ResultSet#fetchChunk()` to fix this. Testing: new test added that reproduces the deadlock reliably (may need to raise the number of iterations). Fixes: #241
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When connection is being closed, it closes all statements and all result sets on these statements. All this is done while holding connection lock.
When fetching next chunk, result set needs to take both result set and connection locks. Because of the wrong order of taking these locks, concurrent
close()call on result set, initiated fromConnection#close()was causing a deadlock.This change reorders locks in
ResultSet#fetchChunk()to fix this.Testing: new test added that reproduces the deadlock reliably (may need to raise the number of iterations).
Fixes: #241