slavavrn / summerpractice2021cpp

This code with threads didn't build for me. Most likely, inclide has some additional conditions

To check the functionality of the algorithm, I made a "threadless" branch - the algorithm works correctly.

Changes:

Corrected time counting, since the original example did not take into account the time of writing to the file, and it is very long in C.

After getting rid of the string copy operators, the running time decreased very slightly.

But the substitution of ready-made symbols from the array reduced the execution time by almost 2 times.

На случай, если моя попытка писать на английском ужасна:

Все-таки этот код с тредами у меня не сбилдился. Скорее всего, просто в inclide какие-то условия установлены

Для проверки работоспособности кода сделал ветку threadless - код отрабатывает правильно.

Изменения:

Исправил подсчет времени, поскольку в исходном примере не учитывалось время записи в файл, а оно на Си очень большое.

После избавления от операторов копирования строк время работы уменьшилось совсем незначительно.

А вот подмена готовых символов из массива сократило время выполнения почти в 2 раза

DataArt Summer practice 2021

C++ demo task

###Main goal Speed up the program. Test condition: 4 threads, 512M file.

###Program description Input file contains constant-size (4096B including null-termitation character) lines of letters add digits. The program swap case for letters and add one to each digit except 9 which turns into 0. Output lines are saved in output file.

##Repo Content ###generate_file.py Creates input file: input.data (512M by default) ###process_file.py Does required job. Can be used for consistency check and for comparison c++ and python code performance. ###main.cpp Source code of c++ soluton ###CMakeLists.txt File for project building

##Build the project ###Windows Option 1: Google: how to build cmake project on windows;

Option 2: Create a project in your beloved IDE. Add main.cpp in the project;

Option3: [Download and install Clion IDE] Open CMateLists.txt as a project in Clion.

###Linux Go to console, cd to project directory, run commands:

mkdir build

cd build

cmake ../

make

You may probably need pthread library to be included

##Tips and tricks

• Get rid of unnecessary data copying including implicit (vector.push_bak, string constructor, copy while passing var s in functions)

• Improve process_line algorithm. Get rid of if-statements, for example.

• Make data distribution per thread more cache-friendly. Data for each thread should lay down in memory in one continuous peace to minimise cache misses.

• Try to map file in memory (linux: mmap() windows: https://docs.microsoft.com/en-us/windows/win32/memory/file-mapping)