[ARROW-2490] [C++] input stream locking inconsistent

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.15.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/15706
• Assignee: Antoine Pitrou
• Reporter: Antoine Pitrou
• Created: 21/Apr/18 17:18
• Updated: 11/Jan/23 07:21
• Resolved: 17/Sep/19 08:55

Description

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.

Issue Links

• links to: GitHub Pull Request #5358