Mitigation of Performance Testing Impediments

Here is a list of impediments common to performance testing projects and what load testers can do to proactively prevent (mitigate) them or reactively respond to them.

This is a companion to my pages on LoadRunner, performance monitoring, performance tuning, and reporting.

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The Impediments

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Common Impediments

An impediment is anything that prevents people from doing their job. Here are some impediments that performance testing teams have encountered.

Issue/Risk Impediment	How applicable to you?	How common?	Impact?

	Not - Some - High
A. Unavailability of subject matter / technical experts such as developers and operations staff.		72%	66%
B. Unavailability of applications to test due to delays or defects in the functionality of the system under test.		63%	78%
C. Lack of Connectivity/access to resources due to network security ports being available or other network blockage.		43%	85%
D. The script recorder fails to recognize applications (due to non-standard security apparatus or other complexity in the application).		52%	65%
E. Not enough Test Data to cover unique conditions necessary during runs that usually go several hours.		82%	42%
F. Delays in obtaining or having enough software licenses and hardware in the performance environment testing.		66%	72%
G. Lack of correspondence between versions of applications in performance versus in active development.		75%	82%
H. Managers not familiar with the implications of ad-hoc approaches to performance testing.		72%	92%

Can you spot another impediment not listed? Let me know and I'll add it to this list.

The sections to follow describes the strategies and tactics for avoiding and mitigating them.

Fight Or Flight? Proactive or Reactive?

Some call the list above "issues" which an organization may theoretically face.

Issues become "risks" when they already impact a project.

A proactive management style at a particular organization sees value in investing up-front to ensure that desired outcomes occur rather than "fight fires" which occur without preparation.

A reactive management style at a particular organization believes in "conserving resources" by not dedicating resources to situations that may never occur, and addressing risks when they become actual reality.

This document addresses both alternatives.

Subject Matter Expertise

The Impediment

What documents written are often one or more versions behind what is under development.

Requirements and definitions are necessary to separate whether a particular behavior is intended or is a deviation from that requirement.

Even if load testers have access to up-to-the-minute wiki entries, load testers usually are not free to interact as a peer of developers.

Load testers are usually not considered a part of the development team or even the development process, so are therefore perceived as an intrusion to developers.

To many developers, Performance testers are a nuisence who waste time poking around a system that is "already perfect" or "one we already know that is slow".

What can reactive load testers do?

What can proactive load testers do?

Ideally, load testers participate in the development process from the moment a development team is formed so that they are socially bonded with the developers.

Recognizing that developers are under tight deadlines, the load test team member defines exactly what is needed from the developer and when it is needed.

This requires up-front analysis of the development organization:

the components of the application
which developers work on which component
contact information for each developer
existing documents available and who wrote each document
comments in blogs written by each developer

An executive assigns a "point person" within the development organization who can provide this information.

Assignments for each developer needs to originate from the development manager under whom a developer works for.

No one can serve two masters. For you will hate one and love the other; you will be devoted to one and despise the other.

A business analyst who is familiar with the application's intended behavior makes a video recording of the application using a utility such as Camtasia from ToolSmith. A recording has the advtange of capturing the timing as well as the steps.

The U.S. military developed the web-based CAVNET system to collaborate on innovations to improvise around impediments found in the found.

Availability of applications

The Impediment

The application may not have been built successfully. There are many root causes for bad builds:

Specification of what goes into each build are not accurate or complete.
Resources intended to go into a particular build are not made available.
An incorrect version of a component is built with newer incompatible components.
Build scripts and processes do not recognize these potential errors, leading to build errors.
Inadequate verification of build completeness.

What can reactive load testers do?

Testers switch to another project/application when one application cannot be tested.

What can proactive load testers do?

Have a separate test environment for each version so that work on a prior version can occur when a build is not successful on one particular environment.

Develop a "smoke test" suite to ensure that applications are testable.

Coordinate testing schedules with what is being changed by developers.

Analyze the root causes of why builds are not successful, and track progress on elminating those causes over time.

Connectivity/access to resources

The Impediment

What can reactive load testers do?

Grant unrestricted access to those working on the system.

What can proactive load testers do?

Pre-schedule when those who grant access are available to the project.

Script Recorder Recognition

The Impediment

Such recording mechanisms are designed to recognize only standard protocols going through the wire.

Standard recording mechanisms will not recognize custom communications, especially within applications using advanced security mechanisms.

Standard recording mechanisms also have difficulty recognizing complex use of Javascript or CSS syntax in SAP portal code.

What can reactive load testers do?

What can proactive load testers do?

Define the pattern install them before locking down the system.

Test Data

The Impediment

Using the same value repeatedly during load testing does not create a realistic emulation of actual behavior because most modern systems cache data in memory, which is 100 times faster than retrieving data from a hard drive.

This discussion also includes role permissions having a different impact on the system. For example, the screen of an administrator or manager would have more options. The more options, the more resources it takes just to display the screen as well as to edit input fields.

A wide variation in data values forces databases to take time to scan through files. Specifying an index used to retrieve data is the most common approach to make applications more efficient.

Growth in the data volume handled by a system can render indexing schemes inefficient at the new level of data.

What can reactive load testers do?

Qualify results from each test with the amount of data used to conduct each test.

Use trial-and-error approachs to finding combinations of values which meet field validation rules.

Examine application source code to determine the rules.

Analyze existing logs to define the distribution of function invocations during test runs.

What can proactive load testers do?

Define procedures for growing the database size, using randomized data values in names.

Test Environment

The Impediment

In order to avoid overloading the production network, the load testing enviornment is often setup so no communication is possible to the rest of the network. This makes it difficult to deploy resources into the environment and then retrieve run result files from the environment.

A closed environment requires its own set of utility services such as DNS, authentication (LDAP), time sychronization, etc.

What can reactive load testers do?

Use the production fail-over environment temporarily and hope that it is not needed during the test.

What can proactive load testers do?

Correspondance Between Versions

The Impediment

reproducible

Developers may have moved on to a different version, different projects, or even different employers.

What can reactive load testers do?

What can proactive load testers do?

Run load tests with trace logs information. This would not duplicate how the system is actually run in production mode.

Ad-hoc Approaches

The Impediment

But the profession of performance and load testing has not matured to that point.

The closest industry document, ITIL, is not yet universally adopted. And ITIL does not clarify the work of performance testing in much detail.

Consequently, each individual involved with load testing is likely to have his/her own opinions about what actions should be taken.

This makes rational exploration of the implications of specific courses of action a conflict-ridden and thus time-consuming and expensive endeavor.

What can reactive load testers do?

Revise project completion estimates or scope as new information becomes available.

What can proactive load testers do?

Identify alternative approaches and analyze them before managers come up with it themselves.

Up-front, identify how to contact each stakeholder and keep them updated at least weekly, and immediately if decisions impact what they are actively working on.

If a new manager is inserted in the project after it starts, review the project plan and rationale for its elements.