The disableMutex variable is not thread-safe as it is globally referenced but not protected by a mutex.

That said, rather than fix this issue, I suggest we remove the client mutex entirely. Evidence this is safe:

1. SQLite3 is thread-safe by default.
2. The SQLite3 library we use ensures the DB was compiled for thread-safety.
3. All tests pass still pass after removing the mutex.
4. Running registry upload bulk discovery --jobs 100 is successful after removing the mutex.