Instrumentation (computer programming) explained

In computer programming, instrumentation is the act of modifying software so that analysis can be performed on it.

Generally, instrumentation either modifies source code or binary code.

Instrumentation enables profiling: ^[1] measuring dynamic behavior during a test run. This is useful for properties of a program that cannot be analyzed statically with sufficient precision, such as performance and alias analysis.

Instrumentation can include:

• Logging events such failures and operation start and end ^[2]
• Measuring and logging the duration of operations

Limitations

Instrumentation is limited by execution coverage. If the program never reaches a particular point of execution, then instrumentation at that point collects no data. For instance, if a word processor application is instrumented, but the user never activates the print feature, then the instrumentation can say nothing about the routines which are used exclusively by the printing feature.

Some types of instrumentation may cause a dramatic increase in execution time. This can limit the application of instrumentation to debugging contexts.

See also

• Hooking – range of techniques used to alter or augment the behavior of an operating system, of applications, or of other software components by intercepting function calls or messages or events passed between software components.
• Instruction set simulator – simulation of all instructions at machine code level to provide instrumentation
• Runtime intelligence – technologies, managed services and practices for the collection, integration, analysis, and presentation of application usage levels, patterns, and practices.
• Software performance analysis – techniques to monitor code performance, including instrumentation.
• Hardware performance counter
• DTrace – A comprehensive dynamic tracing framework for troubleshooting kernel and application problems on production systems in real time, implemented in Solaris, macOS, FreeBSD, and many other platforms and products.
• Java Management Extensions (JMX) – Java technology for managing and monitoring applications, system objects, devices (such as printers), and service-oriented networks.
• Application Response Measurement – standardized instrumentation API for C and Java.
• Dynamic recompilation – a feature of some emulators and virtual machines where the system may recompile some part of a program during execution.

References

• Introduction to Instrumentation and Tracing: Microsoft Developer Network
• Apple Developer Tools: Introduction to Instruments
• SystemTap provides free software (GPL) infrastructure to simplify the gathering of information about the running Linux system.
• cwrap Auto wrap C and C++ functions with instrumentation.

Notes and References

1. Web site: Commenting, Testing, and Instrumenting Code. January 3, 2011. January 29, 2014.
2. http://pic.dhe.ibm.com/infocenter/rtrthelp/v8r0m0/index.jsp?topic=%2Fcom.ibm.rational.testrt.doc%2Ftopics%2Fcinstruovw.html Source Code Instrumentation Overview at IBM website