It is unsafe to assert from the spawned threads in unit-tests, as such assertions are process fatal. We should change the assertions in thread_context_test (e.g., here) to be thread-safe. This could be done by using the ThreadAssertionMonitor.

Moreover, the spawned threads could access non-thread safe metrics (shown below) that are defined here. Accessing these metrics must be serialized (e.g., by using atomics or a mutex) to ensure thread-safety.

class ThreadContextTest : public unittest::Test {
...
private:
    size_t _created;
    size_t _destroyed;
    size_t _destroyedOffThread;
};