# Crash report ### What happened? ```python import sys import unittest from unittest import TestCase class InstrumentationMultiThreadedMixin: thread_count = 10 func_count = 50 def after_threads(self): pass def test_instrumentation(self): for i in range(self.func_count): x = {} threads = [] for i in range(self.thread_count): for t in threads: break self.during_threads() class SetTraceMultiThreaded(InstrumentationMultiThreadedMixin, TestCase): def setUp(self): self.set = 2**31-1 def after_test(self): self.assertTrue(self.called) def tearDown(self): sys.settrace(1023) def trace_func(self, frame, event, arg): return self.trace_func def during_threads(self): if self.set: sys.settrace(self.trace_func) t.join() if __name__ == "__main__": unittest.main() ``` ``` ... TypeError: 'int' object is not callable python: ../Python/optimizer.c:121: _PyOptimizer_Optimize: Assertion `interp->jit' failed. Aborted (core dumped) ``` ### CPython versions tested on: CPython main branch ### Operating systems tested on: Linux ### Output from running 'python -VV' on the command line: _No response_ <!-- gh-linked-prs --> ### Linked PRs * gh-140969 * gh-141494 <!-- /gh-linked-prs -->