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GeezerVison is showing github.com — gh-117755: Remove tests on huge memory allocations by vstinner · Pull Request #117938 · python/cpython

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@vstinner

@vstinner vstinner commented Apr 16, 2024 •
edited by bedevere-app Bot
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Remove unreliable tests on huge memory allocations:

  • Remove test_maxcontext_exact_arith() of test_decimal. Stefan Krah, test author, agreed on removing the test: mimalloc should fail to allocate 784 271 641 GiB: test_decimal killed by the Linux kernel with OOM on a Free Threading build #114331 (comment)
  • Remove test_constructor() tests of test_io. Sam Gross suggests remove them: gh-117755: Fix mimalloc for huge allocation on s390x #117809 (review)

On Linux, depending how overcommit is configured, especially on Linux s390x, a huge memory allocation (half or more of the full address space) can succeed, but then the process will eat the full system swap and make the system slower and slower until the whole system becomes unusable.

Moreover, these tests had to be skipped when Python is built with sanitizers.

  • Issue: Python 3.13.0a6 freethreading on s390x: test.test_io.CBufferedReaderTest.test_constructor crash with Floating point exception #117755

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@vstinner
pythongh-117755: Remove tests on huge memory allocations
cf45a92 
Remove unreliable tests on huge memory allocations:

* Remove test_maxcontext_exact_arith() of test_decimal.
  Stefan Krah, test author, agreed on removing the test:
  python#114331 (comment)
* Remove test_constructor() tests of test_io.
  Sam Gross suggests remove them:
  python#117809 (review)

On Linux, depending how overcommit is configured, especially on Linux
s390x, a huge memory allocation (half or more of the full address
space) can succeed, but then the process will eat the full system
swap and make the system slower and slower until the whole system
becomes unusable.

Moreover, these tests had to be skipped when Python is built with
sanitizers.
@vstinner
vstinner requested a review from rhettinger as a code owner April 16, 2024 16:12
@bedevere-app bedevere-app Bot added tests Tests in the Lib/test dir awaiting core review labels Apr 16, 2024
@bedevere-app bedevere-app Bot mentioned this pull request Apr 16, 2024
Python 3.13.0a6 freethreading on s390x: test.test_io.CBufferedReaderTest.test_constructor crash with Floating point exception #117755
Closed
@vstinner vstinner mentioned this pull request Apr 16, 2024
gh-117755: Fix mimalloc for huge allocation on s390x #117809
Merged
@vstinner vstinner added the skip news label Apr 16, 2024
@vstinner

vstinner commented Apr 16, 2024

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cc @colesbury
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@vstinner

vstinner commented Apr 16, 2024

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@colesbury: Are you ok to remove these tests?
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colesbury
colesbury approved these changes Apr 16, 2024
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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting core review labels Apr 16, 2024
@vstinner
vstinner merged commit e05d202 into python:main Apr 16, 2024
@vstinner
vstinner deleted the remove_big_alloc_tests branch April 16, 2024 20:05
@bedevere-app bedevere-app Bot removed the awaiting merge label Apr 16, 2024
@vstinner

vstinner commented Apr 16, 2024

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Merged, thanks for the confirmation @colesbury.
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diegorusso pushed a commit to diegorusso/cpython that referenced this pull request Apr 17, 2024
@vstinner @diegorusso
pythongh-117755: Remove tests on huge memory allocations (python#117938)
80cd6a2 
Remove unreliable tests on huge memory allocations:

* Remove test_maxcontext_exact_arith() of test_decimal.
  Stefan Krah, test author, agreed on removing the test:
  python#114331 (comment)
* Remove test_constructor() tests of test_io.
  Sam Gross suggests remove them:
  python#117809 (review)

On Linux, depending how overcommit is configured, especially on Linux
s390x, a huge memory allocation (half or more of the full address
space) can succeed, but then the process will eat the full system
swap and make the system slower and slower until the whole system
becomes unusable.

Moreover, these tests had to be skipped when Python is built with
sanitizers.
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@colesbury colesbury colesbury approved these changes
@rhettinger rhettinger Awaiting requested review from rhettinger

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@vstinner @colesbury
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