# dataGen 增加 multiprocessing 函數 問題整理

## random 函數的問題
- fullprocess

    def full_process(n):

    id = os.getpid()
    if not os.path.exists(f'{id}'):
        os.system(f'cp -r OpenFOAM {id}')

    print("%s: Start the task" %(time.strftime('%X')))
    print("Run {}:".format(n))

    fileNumber = np.random.randint(0, len(files))
    basename = os.path.splitext( os.path.basename(files[fileNumber]) )[0]
    print("\tusing {}".format(files[fileNumber]))

    length = freestream_length * np.random.uniform(1.,freestream_length_factor) 
    angle  = np.random.uniform(-freestream_angle, freestream_angle) 
    fsX =  math.cos(angle) * length
    fsY = -math.sin(angle) * length

    print("\tUsing len %5.3f angle %+5.3f " %( length,angle )  )
    print("\tResulting freestream vel x,y: {},{}".format(fsX,fsY))


    os.chdir(f'{id}')
    if genMesh("../" + airfoil_database + files[fileNumber]) != 0:
        print("\tmesh generation failed, aborting")
        os.chdir("..")
        exit(1)

    runSim(fsX, fsY)
    os.chdir("..")
    n = int(n)
    outputProcessing(basename, fsX, fsY, imageIndex=n)
    print("%s: Done" %(time.strftime('%X')))

如果把產生 fsX, fsY 幾個函數的程式碼寫進迴圈中會因為平行運算的關係
使得用到的 random 函式中產生的亂數都會是相同的

- main

    if __name__=='__main__':
    pool = mp.Pool(cpu_to_use)
    startTime = time.time()
    
    for n in range(samples):

        r = pool.apply_async(full_process, args=(n, ))
        #r.wait()

    pool.close()
    pool.join()
    totalTime = (time.time() - startTime)/60
    print(f'Final time elapsed: {totalTime:.2f} minutes')

- Output


## genMesh runSim postprocessing 不會執行

- 問題
可能是 apply_async 的 arguments 問題

- code

    def full_process(basename, fsX, fsY, n):

        id = os.getpid()
        if not os.path.exists(f'{id}'):
            os.system(f'cp -r OpenFOAM {id}')

       print("%s: Start the task" %(time.strftime('%X')))
        print("Run {}:".format(n))


        os.chdir(f'{id}')
        if genMesh("../" + airfoil_database + files[fileNumber]) != 0:
            print("\tmesh generation failed, aborting")
            os.chdir("..")
            exit(1)

        status = runSim(fsX, fsY)
        os.chdir("..")
        n = int(n)
        if status ==0:
            outputProcessing(basename, fsX, fsY, id, imageIndex=n)
            print("%s: Done" %(time.strftime('%X')))

        return id

    ids = []
    def log_id(id):
        if id == -1 : return 
        if id not in ids:
            ids.append(id)

    def main():
        pool = mp.Pool(cpu_to_use)
        startTime = time.time()

        for n in range(samples):
            fileNumber = np.random.randint(0, len(files))
            basename = os.path.splitext( os.path.basename(files[fileNumber]) )[0]
            print("\tusing {}".format(files[fileNumber]))

            length = freestream_length * np.random.uniform(1.,freestream_length_factor) 
            angle  = np.random.uniform(-freestream_angle, freestream_angle) 
            fsX =  math.cos(angle) * length
            fsY = -math.sin(angle) * length

            print("\tUsing len %5.3f angle %+5.3f " %( length,angle )  )
            print("\tResulting freestream vel x,y: {},{}".format(fsX,fsY))

            pool.apply_async(full_process, args=(basename, fsX, fsY), callback=log_id)

        pool.close()
        pool.join()
        totalTime = (time.time() - startTime)/60
        print(f'Final time elapsed: {totalTime:.2f} minutes')
        print(ids)
        for id in ids:
            os.system(f'rm -r {id}/')

    if __name__=='__main__':
        main()

- Output