test_typing: test_many_weakrefs takes many seconds #110178
Description
Bug report
Bug description:
TypeVarTests.test_many_weakrefs in test_typing takes far longer than any other test in test_typing if you're using a debug build of CPython, slowing down test_typing considerably:
>python Lib/test/test_typing.py --durations 5
Running Debug|x64 interpreter...
.............................................................................................................................................................................................................................................s.....................................................................................................................................................................................................................................................................................................................................................................
Slowest test durations
----------------------------------------------------------------------
5.090s test_many_weakrefs (__main__.TypeVarTests.test_many_weakrefs)
0.206s test_variadic_parameters (__main__.GenericAliasSubstitutionTests.test_variadic_parameters)
0.082s test_two_parameters (__main__.GenericAliasSubstitutionTests.test_two_parameters)
0.057s test_special_attrs (__main__.SpecialAttrsTests.test_special_attrs)
0.044s test_var_substitution (__main__.TypeVarTupleTests.test_var_substitution)
----------------------------------------------------------------------
Ran 594 tests in 6.714s
OK (skipped=1)
The test was added in #108517, as a regression test for #108295.
The slowdown caused by this test is much less pronounced if you use a PGO-optimised non-debug build, but the test still takes much longer than any other test in test_typing on my machine:
>python Lib/test/test_typing.py --durations 5
Running PGUpdate|x64 interpreter...
.............................................................................................................................................................................................................................................s.....................................................................................................................................................................................................................................................................................................................................................................
Slowest test durations
----------------------------------------------------------------------
0.379s test_many_weakrefs (__main__.TypeVarTests.test_many_weakrefs)
0.026s test_variadic_parameters (__main__.GenericAliasSubstitutionTests.test_variadic_parameters)
0.014s test_two_parameters (__main__.GenericAliasSubstitutionTests.test_two_parameters)
0.007s test_etree (__main__.UnionTests.test_etree)
0.004s test_var_substitution (__main__.TypeVarTupleTests.test_var_substitution)
----------------------------------------------------------------------
Ran 594 tests in 0.610s
OK (skipped=1)
The test currently attempts to create 100,000 TypeVar weakrefs, 100,000 ParamSpec weakrefs and 100,000 TypeVarTuple weakrefs:
cpython/Lib/test/test_typing.py
Lines 547 to 555 in 038c356
@JelleZijlstra, reckon we could maybe make that number a little smaller? :)
CPython versions tested on:
CPython main branch
Operating systems tested on:
Windows