Database Reference
In-Depth Information
by default. It is then incremented by another configurable parameter
increment
after
every round of testing, the CARE framework currently sets the default value to 200
for the high stress test strategy, and 0 for the low stress test strategy. For example,
for the high stress test strategy, after the initial 6 rounds, the number of concurrent
threads fired by one end-user would go from 100 to 300, 500, 700, 900 and 1,100
in successive rounds. Therefore, a maximum of 3,300 concurrent threads can be
achieved since 3 end-users are applied in the evaluation.
For the high stress test strategy, a number of continuous requests are sent within
every thread to maintain its stress on the cloud platform over a period of time. If
only a single request is sent to the cloud in each thread, our observation is that the
expected concurrent stress cannot always be reached, and due to network latency
and variability, the arrival time and order of packets at the cloud platform can vary
widely. Hence in the CARE framework, another configurable parameter
continuous
request
is provided with a default value of 3, striking a balance of providing a more
sustained and even workload to the cloud and enabling the test to be conducted
across different concurrent clients.
Lastly, as cloud computing is essentially a large-scale shared system, where
the typical cloud end-user would be using a publicly shared network in order to
access cloud services, it must be that there can be variations in network capacity,
bandwidth, and latency issues, that fluctuates over time. The CARE framework
thus provides a scheduler that support scheduled
cron
1
jobs to be automatically and
repeatedly activated to retrieved testing samples across different times over a 24 h
period.
The flow chart of the low stress test strategy for requests is essentially a simplified
version of the high stress strategy shown in Fig.
4.2
, with the difference being that
the multi-threaded functions are deactivated.
Building a Test Set with CARE
By using the CARE framework, it is possible to combine the various test scenarios
with the various load test strategies to produce a comprehensive test set.
While the test set can be designed and created using the CARE framework
depending on the precise test requirement, the CARE framework also comes with
a reusable test set that aims to provide the test coverage of a large number of
commonly found cloud application types. Table
4.1
illustrates a view of all test sets.
Firstly, there are five Contract-First Web Service based test methods, namely high
stress round-trip, low stress database read and write, and high stress database read
and write. There are also three RESTful Web Service based methods, low stress
large file read, write and delete, respectively. The four key methods in the test set
are listed in Table
4.1
.
