[jira] [Commented] (ARROW-18084) [Python] "CSV parser got out of sync with chunker" on subsequent batches regardless of block size

["Antoine Pitrou (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-18084?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17619345#comment-17619345 ] 

Antoine Pitrou commented on ARROW-18084:
----------------------------------------

Can you try passing {{newlines_in_values=True}}? Chances are this dataset contains embedded newlines in CSV values.
See https://arrow.apache.org/docs/python/generated/pyarrow.csv.ParseOptions.html#pyarrow.csv.ParseOptions

> [Python] "CSV parser got out of sync with chunker" on subsequent batches regardless of block size
> -------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-18084
>                 URL: https://issues.apache.org/jira/browse/ARROW-18084
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++, Python
>    Affects Versions: 7.0.0, 9.0.0
>         Environment: Ubuntu Linux
> pyarrow 9.0.0 installed with pip (manylinux wheel)
> Python 3.9.0 from conda-forge
> GCC 9.4.0
>            Reporter: Juan Luis Cano Rodríguez
>            Priority: Major
>         Attachments: Screenshot 2022-10-18 at 10-11-29 JupyterLab · Orchest.png
>
>
> I'm trying to read a specific large CSV file ({{the-reddit-climate-change-dataset-comments.csv}} from [this dataset|https://www.kaggle.com/datasets/pavellexyr/the-reddit-climate-change-dataset]) by batches. This is my code:
> {code:python}
> import os
> import pyarrow as pa
> from pyarrow.csv import open_csv, ReadOptions
> import pyarrow.parquet as pq
> filename = "/data/reddit-climate/the-reddit-climate-change-dataset-comments.csv"
> print(f"Reading {filename}...")
> mmap = pa.memory_map(filename)
> reader = open_csv(mmap)
> while True:
>     try:
>         batch = reader.read_next_batch()
>         print(len(batch))
>     except StopIteration:
>         break
> {code}
> But, after a few batches, I get an exception:
> {noformat}
> Reading /data/reddit-climate/the-reddit-climate-change-dataset-comments.csv...
> 1233
> 1279
> 1293
> ---------------------------------------------------------------------------
> ArrowInvalid                              Traceback (most recent call last)
> Input In [1], in <cell line: 14>()
>      13 while True:
>      14     try:
> ---> 15         batch = reader.read_next_batch()
>      16         print(len(batch))
>      17     except StopIteration:
> File /opt/conda/lib/python3.9/site-packages/pyarrow/ipc.pxi:683, in pyarrow.lib.RecordBatchReader.read_next_batch()
> File /opt/conda/lib/python3.9/site-packages/pyarrow/error.pxi:100, in pyarrow.lib.check_status()
> ArrowInvalid: CSV parser got out of sync with chunker
> {noformat}
> I have tried changing the block size, but I always end up with that error sooner or later:
> - With {{read_options=ReadOptions(block_size=10_000)}}, it reads 1 batch of 11 rows and then crashes
> - With 100_000, 103 rows and then crashes
> - 1_000_000: 1164 rows and then crashes
> - 10_000_000: 12370 rows and then crashes
> I am not sure what else to try here. According to [the C++ source code|https://github.com/apache/arrow/blob/cd33544533ee7d70cd8ff7556e59ef8f1d33a176/cpp/src/arrow/csv/reader.cc#L266-L267], this "should not happen".
> I have tried with pyarrow 7.0 and 9.0, identical result and traceback.



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