diff options
| -rw-r--r-- | numpy/fft/fftpack.py | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/numpy/fft/fftpack.py b/numpy/fft/fftpack.py index 7ee0e4bea..236a18d7a 100644 --- a/numpy/fft/fftpack.py +++ b/numpy/fft/fftpack.py @@ -53,6 +53,9 @@ def _raw_fft(a, n=None, axis=-1, init_function=fftpack.cffti, raise ValueError("Invalid number of FFT data points (%d) specified." % n) try: + # Thread-safety note: We rely on list.pop() here to atomically + # retrieve-and-remove a wsave from the cache. This ensures that no + # other thread can get the same wsave while we're using it. wsave = fft_cache.setdefault(n, []).pop() except (IndexError): wsave = init_function(n) @@ -76,7 +79,12 @@ def _raw_fft(a, n=None, axis=-1, init_function=fftpack.cffti, r = work_function(a, wsave) if axis != -1: r = swapaxes(r, axis, -1) + + # As soon as we put wsave back into the cache, another thread could pick it + # up and start using it, so we must not do this until after we're + # completely done using it ourselves. fft_cache[n].append(wsave) + return r |