[jira] [Updated] (ARROW-2490) [C++] input stream locking inconsistent

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

     [ https://issues.apache.org/jira/browse/ARROW-2490?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wes McKinney updated ARROW-2490:
--------------------------------
    Fix Version/s: 0.14.0

> [C++] input stream locking inconsistent
> ---------------------------------------
>
>                 Key: ARROW-2490
>                 URL: https://issues.apache.org/jira/browse/ARROW-2490
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++
>    Affects Versions: 0.9.0
>            Reporter: Antoine Pitrou
>            Priority: Major
>             Fix For: 0.14.0
>
>
> Reading from the current file pointer is inherently thread-unsafe, since the file pointer may be updated by another thread (either before or during the operation). However, currently, we have:
> * {{ReadableFile::Read}} takes a lock
> * {{MemoryMappedFile::Read}} doesn't take a lock
> * {{BufferReader::Read}} doesn't take a lock
> We could always take a lock in {{Read}}. But I don't think there's a pattern where it's useful to call {{Read}} from multiple threads at once (since you're not sure where the file pointer will be exactly when the read starts). So we could as well specify that {{Read}} isn't thread-safe and let people make sure they don't call it from multiple threads.



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