Increasing read chunk size could improve performance for large responses #135

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1. florimondmanca commented on Aug 5, 2020

   

   florimondmanca

   on Aug 5, 2020

   Last edited by florimondmanca

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   Running the 1MB-response benchmark for various READ_NUM_BYTES values, and a matplotlib script later, here's a handy little plot to support this assessment that 64kB is probably a good value…

   import matplotlib.pyplot as plt
   
   data = [
       (4, 2.36, 2.13),
       (16, 1.18, 0.99),
       (32, 1.07, 0.94),
       (64, 0.95, 0.81),
       (96, 0.87, 0.74),
       (128, 0.82, 0.68),
       (160, 0.80, 0.66),
   ]
   
   x, runtime, cpu = zip(*data)
   
   plt.grid()
   plt.xlabel("READ_NUM_BYTES (kB)")
   plt.xticks(range(0, 192, 16))
   plt.ylim(0, 3)
   plt.ylabel("Median execution time (s)")
   plt.scatter(x, runtime)
   plt.scatter(x, cpu)
   plt.legend(["runtime", "cpu"])
   plt.show()

   

   Looks like the median execution time gets exponentially smaller as we increase the chunk size. Once we hit 32kB the marginal improvement starts hitting its limits. 64kB gets us "below 1s in wall time for a 1MB response" and that sounds very satisfying. :-)
2. dalf commented on Aug 5, 2020

   

   dalf

   on Aug 5, 2020

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   An additional graph (made using this tool):
   

   • httpcore_True_*: http2=True
   • httpcore_False_* : http2=False

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3. lovelydinosaur

   closed this as completedin #136on Aug 5, 2020