Enterprise Library Test Guide - Willy .Net

Using the Test Cases 243
Verification
Running the two test cases again after applying the preceding code examples verified
that the cost of creating a domain object with the FileConfigurationSource class was
within acceptable limits.
Specific Performance Tests
Specific aspects of each application block were also tested to see if their performance
was acceptable. This section discusses performance issues that were found in the
Data Access Application Block, the Logging Application Block, and the Cryptography
Application Block.
Testing the Logging Application Block
The Logging Application Block was tested to determine the cost of logging messages
to a database trace listener. To pass the test, the cost of logging to a database trace
listener should be scalable. If the number of transactions per second decreases as the
number of requests increases, there is a bottleneck.
Test Case
To run the test case, the application block was first configured to use a database trace
listener to log messages to a database. The test case logged messages to the database
with the Logger.Write method. A performance test tool was used to analyze the
results.
Problem
The results from the performance test showed that the transactions per second decreased
when the numbers of users increased. This decrease occurred because, with
a large number of users, there was significant contention for access to the database
trace listener.
This contention exists because the LogSource class enumerates through all the trace
listeners that the application block is configured to use and calls each trace listener’s
TraceData method. Before calling the method, the LogSource class first checks to see
whether the trace listeners are thread safe by calling each trace listener’s IsThread-
Safe property. It locks a trace listener if it is not thread safe. The FormattedDatabaseTraceListener
class derives from FormattedTraceListenerBase, which has the
IsThreadSafe property set to false. This means that the FormattedDatabaseTraceListener
class is locked for every call to its TraceData method. This is why there is
contention for access to the database trace listener.