How Can I Get C 17 Parallel Algorithms Working?

Are C 17 Parallel Algorithms Implemented Yet?

Question:

Despite attempting to implement the new parallel library features introduced in the C 17 standard, the author encountered compilation errors. They questioned whether these algorithms had been implemented yet.

Answer:

GCC 9 and TBB 2018 are the first to support the C 17 parallel algorithms. However, TBB must be installed separately.

Installation Instructions:

Ubuntu 19.10:

sudo apt install gcc libtbb-dev
g++ -ggdb3 -O3 -std=c++17 -Wall -Wextra -pedantic -o main.out main.cpp -ltbb
./main.out

Ubuntu 18.04:

# Install GCC 9
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-9 g++-9

# Compile libtbb from source.
sudo apt-get build-dep libtbb-dev
git clone https://github.com/intel/tbb
cd tbb
git checkout 2019_U9
make -j `nproc`
TBB="$(pwd)"
TBB_RELEASE="${TBB}/build/linux_intel64_gcc_cc7.4.0_libc2.27_kernel4.15.0_release"

# Use them to compile our test program.
g++-9 -ggdb3 -O3 -std=c++17 -Wall -Wextra -pedantic -I "${TBB}/include" -L 
"${TBB_RELEASE}" -Wl,-rpath,"${TBB_RELEASE}" -o main.out main.cpp -ltbb
./main.out

Performance Analysis:

Testing on a Lenovo ThinkPad P51 laptop with 4 cores/8 threads and 2x 16GiB RAM, the parallel sort was about 4.5 times faster than the serial version for input sizes of 100 million numbers.

Error Messages:

• If TBB is not installed:

  fatal error: tbb/blocked_range.h: No such file or directory

• If TBB version is too old:

  #error Intel(R) Threading Building Blocks 2018 is required; older versions are not supported.

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