fix: race condition in SpillPool caused by buffered stream #20067
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Signed-off-by: Ahmed hossam <ahmed.hossambahig@gmail.com>
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Pull request overview
This PR fixes an indeterministic test failure in SpillPool caused by a race condition between the writer and reader coordination logic when using a buffered stream.
Changes:
- Removed the
spawn_bufferedwrapper fromread_spill_as_streamto return an unbuffered stream - Removed the unused import of
spawn_bufferedfromspill_manager.rs
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martin-g
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Jan 30, 2026
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martin-g
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If it is not too complex maybe add a test case verifying that there is no racing any more
| max_record_batch_memory, | ||
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| Ok(spawn_buffered(stream, self.batch_read_buffer_capacity)) |
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It seems batch_read_buffer_capacity is no more used.
It could be deprecated or maybe even removed.
https://github.com/dekuu5/datafusion/blob/1b8ef43fdd1424a3e4fe2db213fec4e7228788b0/datafusion/physical-plan/src/sorts/multi_level_merge.rs#L276 is a no-op
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Which issue does this PR close?
SpillPool#20027Rationale for this change
The SpillPool test spill::spill_pool::channel was failing indeterministically due to a race condition between SpillFile's coordination logic and the spawn_buffered background task used in the stream reader.
What changes are included in this PR?
read_spill_as_stream now returns a normal stream not a buffered stream
Are these changes tested?
No, the fix is for an existing test mentioned in the issue. I wasn't able to find the bug initially, but I found it by stress-testing the original test 100 times in parallel.
Are there any user-facing changes?
no
i still think we should add a buffer stream that is aware of the coordination of the writer and reader but i can't warp my head around it yet.