1. Investigating the Impacts of
Web Servers on Web
Application Energy Usage
Computer and Information Sciences
University of Delaware
Irene L. Manotas G.
Cagri Sahin
James Clause
Lori Pollock
Kristina Winbladh

2. Which Web Server Should I Use?
Empirically Investigate
• RQ1—Feasibility: Does the choice of web
server impact the energy consumption of a web
application?
• RQ2—Consistency: Are the web servers
consistent in their impact?
2

3. Experimental Setup
web browser
3
workloads
web server
web application
LEAP
energy
monitor
Integra+on
Tests
Automa+c
Tes+ng
user inputs
3
WEBRick

4. 4
% Difference in energy consumption from the mean
Web Servers
Feature
Mongrel
Puma
Thin
WEBrick
Calendar
10.10
-6.10
-8.50
2.30
Context Edit
-1.40
-2.10
-0.10
3.40
Preferences
-4.00
8.70
-4.00
-1.80
Review
-1.10
-6.30
-1.30
7.70
Search
1.80
4.10
5.90
-0.60
Show Statistics
2.70
6.10
-13.90
2.90
Toggle Context
-3.00
4.70
7.20
-10.70
Total
1.70
0.10
-3.60
1.70
§ A given web server is not always the best under all features.
§ The web server does make a difference
§ Energy consumption variability differs across features.
4
4
This work is supported in part by National Science Foundation Grant No. 1216488 and
an award from the University of Delaware Research Foundation
Results: Feasibility and Consistency

5. • Correlating energy measurements with design
decisions/implementations in a non-tedious manner
5
Issues We Face
Questions for Discussion
• How are others monitoring and mapping energy usage
to program units?
• How many repeated runs do others perform to take
measurements to account for variations?