[omrzk]

Cancelling a parallel SFTP file read or write leaves its outstanding requests running. Closing the SSH connection afterwards can produce unretrieved SFTPConnectionLost task exceptions.

Cancel and gather outstanding requests on every exit from the parallel I/O iterator. Keep completed tasks owned until their results are consumed, so closing the iterator between yielded blocks also retrieves the rest of the batch.

Fixes #845.

Validation: three new loopback cancellation regressions fail on current develop and pass with the fix; they cover read(), write(), and read_parallel() and reuse the same file and connection afterwards. The SFTP suite passes (599 tests, one skip; 377 subtests), and the full suite passes (1,764 tests, 51 skips; 4,249 subtests). All configured pre-commit checks pass on Python 3.12/Linux. Native macOS/Windows and optional unavailable cryptographic backends were not tested locally.

This contribution is provided under the project's EPL-2.0 / GPL-2.0-or-later license terms. Please list the contributor as omrzk.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.87%. Comparing base (fab96ac) to head (afe3aef).
⚠️ Report is 265 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #846      +/-   ##
===========================================
+ Coverage    99.85%   99.87%   +0.02%     
===========================================
  Files           95      102       +7     
  Lines        27784    32750    +4966     
  Branches      2908     3141     +233     
===========================================
+ Hits         27743    32709    +4966     
  Misses          38       38              
  Partials         3        3              

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[ronf]

Thanks very much for the PR! I'm going to add one additional change suggested by Claude to properly clean up the iterator if something inside the loop body raises an exception. Right now, this cleanup only occurs if the iter itself is cancelled.

[ronf]

Additional fix is now in commit f7056ae in "develop".