[jira] [Commented] (ARROW-5791) [Python] pyarrow.csv.read_csv hangs + eats all RAM

["Wes McKinney (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-5791?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16875813#comment-16875813 ] 

Wes McKinney commented on ARROW-5791:
-------------------------------------

Evidently there's an int16 overflow somewhere in the Arrow CSV codebase. An initial grep didn't turn up anything obvious. 

Comparisons with other CSV libraries (like pandas) probably are not relevant since there is no code overlap. 

> [Python] pyarrow.csv.read_csv hangs + eats all RAM
> --------------------------------------------------
>
>                 Key: ARROW-5791
>                 URL: https://issues.apache.org/jira/browse/ARROW-5791
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>    Affects Versions: 0.13.0
>         Environment: Ubuntu Xenial, python 2.7
>            Reporter: Bogdan Klichuk
>            Priority: Major
>         Attachments: csvtest.py, graph.svg, sample_32768_cols.csv, sample_32769_cols.csv
>
>
> I have quite a sparse dataset in CSV format. A wide table that has several rows but many (32k) columns. Total size ~540K.
> When I read the dataset using `pyarrow.csv.read_csv` it hangs, gradually eats all memory and gets killed.
> More details on the conditions further. Script to run and all mentioned files are under attachments.
> 1) `sample_32769_cols.csv` is the dataset that suffers the problem.
> 2) `sample_32768_cols.csv` is the dataset that DOES NOT suffer and is read in under 400ms on my machine. It's the same dataset without ONE last column. That last column is no different than others and has empty values.
> The reason of why exactly this column makes difference between proper execution and hanging failure which looks like some memory leak - no idea.
> I have created flame graph for the case (1) to support this issue resolution (`graph.svg`).
>  



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