s or OpenMP.  Parallelism using MPI or forked processes
involves a separate address-space and global variables for each process,
and is not susceptible to problems of this sort.)

   <p>If you are configured FFTW with the <code>--enable-debug</code> or
<code>--enable-debug-malloc</code> flags (see <a href="Installation-on-Unix.html#Installation-on-Unix">Installation on Unix</a>),
then <code>fftw_execute</code> is not thread-safe.  These flags are not
documented because they are intended only for developing
