Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Arrow up icon
GO TO TOP
Python Web Scraping

You're reading from   Python Web Scraping Hands-on data scraping and crawling using PyQT, Selnium, HTML and Python

Arrow left icon
Product type Paperback
Published in May 2017
Publisher
ISBN-13 9781786462589
Length 220 pages
Edition 2nd Edition
Languages
Tools
Concepts
Arrow right icon
Author (1):
Arrow left icon
Katharine Jarmul Katharine Jarmul
Author Profile Icon Katharine Jarmul
Katharine Jarmul
Arrow right icon
View More author details
Toc

Performance

To further understand how increasing the number of threads and processes affects the time required when downloading, here is a table of results for crawling 500 web pages:

Script Number of threads Number of processes Time Comparison with sequential Errors Seen?
Sequential 1 1 1349.798s 1 N
Threaded 5 1 361.504s 3.73 N
Threaded 10 1 275.492s 4.9 N
Threaded 20 1 298.168s 4.53 Y
Processes 2 2 726.899s 1.86 N
Processes 2 4 559.93s 2.41 N
Processes 2 8 451.772s 2.99 Y
Processes 5 2 383.438s 3.52 N
Processes 5 4 156.389s 8.63 Y
Processes 5 8 296.610s 4.55 Y

The fifth column shows the proportion of time in comparison to the base case of sequential downloading. We can see that the increase in performance is not linearly proportional to the number of threads and processes but appears logarithmic, that is, until adding more threads actually decreases performance. For example, one process...

lock icon The rest of the chapter is locked
Register for a free Packt account to unlock a world of extra content!
A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.
Unlock this book and the full library FREE for 7 days
Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of
Renews at $19.99/month. Cancel anytime
Banner background image