[jira] [Created] (ARROW-14790) Memory leak when reading CSV files

["Sten Larsson (Jira)" <ji...@apache.org>]

Sten Larsson created ARROW-14790:
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             Summary: Memory leak when reading CSV files
                 Key: ARROW-14790
                 URL: https://issues.apache.org/jira/browse/ARROW-14790
             Project: Apache Arrow
          Issue Type: Bug
            Reporter: Sten Larsson


We're having problem with a memory leak in a Ruby script that processes many CSV files. I have written some short scripts do demonstrate the problem: [https://gist.github.com/stenlarsson/60b1e4e99416738b41ee30e7ba294214]

The first script, [arrow_test_csv.rb|https://gist.github.com/stenlarsson/60b1e4e99416738b41ee30e7ba294214#file-arrow_test_csv-rb], creates a 184 MB CSV file for testing.

The second script, [arrow_memory_leak.rb|https://gist.github.com/stenlarsson/60b1e4e99416738b41ee30e7ba294214#file-arrow_memory_leak-rb], then loads the CSV file 10 times using Arrow. It uses the [get_process_mem|https://rubygems.org/gems/get_process_mem] gem to print the memory usage both before and after each iteration. It also invokes the garbage collector on each iteration to ensure the problem is not that Ruby holds on to any objects. This is what it prints on my MacBook Pro using Arrow 6.0.0:
{noformat}
127577 objects, 34.234375 MB
127577 objects, 347.625 MB
127577 objects, 438.7890625 MB
127577 objects, 457.6953125 MB
127577 objects, 469.8046875 MB
127577 objects, 480.88671875 MB
127577 objects, 487.96484375 MB
127577 objects, 493.8359375 MB
127577 objects, 497.671875 MB
127577 objects, 498.55859375 MB
127577 objects, 501.42578125 MB
{noformat}
The third script, [arrow_memory_leak.py |https://gist.github.com/stenlarsson/60b1e4e99416738b41ee30e7ba294214#file-arrow_memory_leak-py] is a Python implementation of the same script. This shows that the problem is not in the Ruby bindings:
{noformat}
2106 objects, 31.75390625 MB
2106 objects, 382.28515625 MB
2106 objects, 549.41796875 MB
2106 objects, 656.78125 MB
2106 objects, 679.6875 MB
2106 objects, 691.9921875 MB
2106 objects, 708.73828125 MB
2106 objects, 717.296875 MB
2106 objects, 724.390625 MB
2106 objects, 729.19921875 MB
2106 objects, 734.47265625 MB
{noformat}
I have also tested Arrow 5.0.0 and it has the same problem.



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