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https://issues.apache.org/jira/browse/ARROW-10029?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David McGuire updated ARROW-10029:
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Attachment: repro.py
> Deadlock in the interaction of pyarrow FileSystem and ParquetDataset
> --------------------------------------------------------------------
>
> Key: ARROW-10029
> URL: https://issues.apache.org/jira/browse/ARROW-10029
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Affects Versions: 1.0.1
> Reporter: David McGuire
> Priority: Major
> Attachments: repro.py
>
>
> @martindurant good news (for you): I have a repro test case that is 100%
> {{pyarrow}}, so it looks like {{s3fs}} is not involved.
> @jorisvandenbossche how should I follow up with this, based on
> {{pyarrow.filesystem.LocalFileSystem}}?
> Viewing the File System *directories* as a tree, one thread is required for
> every non-leaf node, in order to avoid deadlock.
> 1) dataset
> 2) dataset/foo=1
> 3) dataset/foo=1/bar=2
> 4) dataset/foo=1/bar=2/baz=0
> 5) dataset/foo=1/bar=2/baz=1
> 6) dataset/foo=1/bar=2/baz=2
> *) dataset/foo=1/bar=2/baz=0/qux=false
> *) dataset/foo=1/bar=2/baz=1/qux=false
> *) dataset/foo=1/bar=2/baz=1/qux=true
> *) dataset/foo=1/bar=2/baz=0/qux=true
> *) dataset/foo=1/bar=2/baz=2/qux=false
> *) dataset/foo=1/bar=2/baz=2/qux=true
> {quote}
> import pyarrow.parquet as pq
> import pyarrow.filesystem as fs
> class LoggingLocalFileSystem(fs.LocalFileSystem):
> def walk(self, path):
> print(path)
> return super().walk(path)
> fs = LoggingLocalFileSystem()
> dataset_url = "dataset"
> threads = 6
> dataset = pq.ParquetDataset(dataset_url, filesystem=fs,
> validate_schema=False, metadata_nthreads=threads)
> print(len(dataset.pieces))
> threads = 5
> dataset = pq.ParquetDataset(dataset_url, filesystem=fs,
> validate_schema=False, metadata_nthreads=threads)
> print(len(dataset.pieces))
> {quote}
> *_Call with 6 threads completes._*
> *_Call with 5 threads hangs indefinitely._*
> {quote}
> $ python repro.py
> dataset
> dataset/foo=1
> dataset/foo=1/bar=2
> dataset/foo=1/bar=2/baz=0
> dataset/foo=1/bar=2/baz=1
> dataset/foo=1/bar=2/baz=2
> dataset/foo=1/bar=2/baz=0/qux=false
> dataset/foo=1/bar=2/baz=0/qux=true
> dataset/foo=1/bar=2/baz=1/qux=false
> dataset/foo=1/bar=2/baz=1/qux=true
> dataset/foo=1/bar=2/baz=2/qux=false
> dataset/foo=1/bar=2/baz=2/qux=true
> 6
> dataset
> dataset/foo=1
> dataset/foo=1/bar=2
> dataset/foo=1/bar=2/baz=0
> dataset/foo=1/bar=2/baz=1
> dataset/foo=1/bar=2/baz=2
> ^C
> ...
> KeyboardInterrupt
> ^C
> ...
> KeyboardInterrupt
> {quote}
> **NOTE:** this *also* happens with the un-decorated {{LocalFileSystem}}, and
> when omitting the {{filesystem}} argument.
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