NTHREADS != 1 ignored: this build of SExtractor is single-threaded

[Schwarzam]

Hi, I'm trying to create a multithreaded installation of sextractor but I cant seem to get it.

I already tried on both ubuntu and Fedora, and building all the packages from source, including fftw3 with --enable-threads and --enable-float flags.

When I run sextractor it always gives me:

WARNING: NTHREADS != 1 ignored: this build of SExtractor is single-threaded

I just can't get it, does any one has a recipe to do this?

Finally i'm building in a docker container, so If I get it I can share.

FROM ubuntu:22.04

RUN apt update
RUN apt install -y git wget

RUN DEBIAN_FRONTEND=noninteractive TZ=Etc/UTC apt-get -y install tzdata

RUN apt install -y autoconf automake libtool 
RUN apt install -y make

RUN apt-get update -y \
    && apt-get upgrade -y \
    && apt-get -y install build-essential \
        zlib1g-dev \
        libncurses5-dev \
        libgdbm-dev \ 
        libnss3-dev \
        libssl-dev \
        libreadline-dev \
        libffi-dev \
        libsqlite3-dev \
        libbz2-dev \
        wget \
    && export DEBIAN_FRONTEND=noninteractive \
    && apt-get purge -y imagemagick imagemagick-6-common

RUN wget https://heasarc.gsfc.nasa.gov/FTP/software/fitsio/c/cfitsio-4.5.0.tar.gz
RUN tar -xf cfitsio-4.5.0.tar.gz
RUN cd cfitsio-4.5.0 && ./configure --prefix=/usr/local && make && make install
RUN ln -s /usr/local/lib/libcfitsio.so.9 /usr/lib/libcfitsio.so.9

RUN git clone https://github.com/OpenMathLib/OpenBLAS

WORKDIR /OpenBLAS
RUN make USE_OPENMP=1 USE_THREAD=1 USE_LAPACK=1 INTERFACE64=0
RUN make PREFIX=/usr/local install

RUN echo "/usr/local/lib" > /etc/ld.so.conf.d/openblas.conf && ldconfig


RUN apt install gfortran -y

WORKDIR /

RUN wget https://fftw.org/pub/fftw/fftw-3.3.10.tar.gz
RUN tar -xvf fftw-3.3.10.tar.gz
WORKDIR /fftw-3.3.10
RUN ./configure --enable-threads --enable-float
RUN make -j 8 && make install

RUN ldconfig

# Clone and build SExtractor
WORKDIR /
RUN git clone https://github.com/astromatic/sextractor.git
WORKDIR /sextractor
RUN sh autogen.sh
RUN ./configure \
    --enable-threads \

    --with-fftw-libdir=/usr/local/lib \
    --with-fftw-incdir=/usr/local/include \

    --enable-openblas \
    --with-openblas-libdir=/usr/local/lib \
    --with-openblas-incdir=/usr/local/include \

    --enable-threads 

RUN make -j4 && make install

# Verify linkage
RUN ldd /usr/local/bin/sex

# Set runtime environment
ENV LD_LIBRARY_PATH="/usr/local/lib:$LD_LIBRARY_PATH"

CMD ["sex"]
#sudo docker build -t nwmar .
#docker run --rm -v $(pwd):/data nwmar sourcextractor++

[ebertin]

Hi @Schwarzam,
indeed the --enable-threads option in SExtractor was deactivated (with this line) a while ago as it prove to be actually detrimental to performance in most cases (threading is essentially limited to the FFTs used for convolution in model-fitting). When processing large numbers of images it is generally much more efficient to run several instances of SExtractor in an embarrassingly parallel way. You can get a better performance boost (~+40%) by simply recompiling the code with the free Intel icx compiler and MKL library (--enable-mkl configure option).
However, it appears the issue you faced when trying to build the threaded version appeared to be related to a typo I just fixed in the new threads branch. You might want to check it out and see if you reach the same conclusions regarding the impact of multithreading. Thanks!

[Schwarzam]

Thank you very much for the clarification!