Probe effect is an unintended alteration in system behavior caused by measuring that system. In code profiling and performance measurements, the delays introduced by insertion or removal of code instrumentation may result in a non-functioning application, or unpredictable behavior.
Examples
In electronics, by attaching a
multimeter
A multimeter (also known as a multi-tester, volt-ohm-milliammeter, volt-ohmmeter or VOM, avometer or ampere-volt-ohmmeter) is a measuring instrument that can measure multiple electrical properties. A typical multimeter can measure voltage, elec ...
,
oscilloscope
An oscilloscope (formerly known as an oscillograph, informally scope or O-scope) is a type of electronic test instrument that graphically displays varying voltages of one or more signals as a function of time. Their main purpose is capturing i ...
, or other testing device via a
test probe
A test probe is a physical device used to connect electronic test equipment to a device under test (DUT). Test probes range from very simple, robust devices to complex probes that are sophisticated, expensive, and fragile. Specific types includ ...
, small amounts of
capacitance
Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related ...
,
resistance, or
inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The electric current produces a magnetic field around the conductor. The magnetic field strength depends on the magnitude of the ...
may be introduced. Though good scopes have very slight effects, in sensitive circuitry these can lead to unexpected failures, or conversely, unexpected fixes to failures.
In
debugging
In engineering, debugging is the process of finding the Root cause analysis, root cause, workarounds, and possible fixes for bug (engineering), bugs.
For software, debugging tactics can involve interactive debugging, control flow analysis, Logf ...
of
parallel
Parallel may refer to:
Mathematics
* Parallel (geometry), two lines in the Euclidean plane which never intersect
* Parallel (operator), mathematical operation named after the composition of electrical resistance in parallel circuits
Science a ...
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
programs, sometimes failures (such as
deadlock
Deadlock commonly refers to:
* Deadlock (computer science), a situation where two processes are each waiting for the other to finish
* Deadlock (locksmithing) or deadbolt, a physical door locking mechanism
* Political deadlock or gridlock, a si ...
s) are not present when the debugger's code (which was meant to help to find a reason for deadlocks by visualising points of interest in the program code) is attached to the program. This is because additional code changed the timing of the execution of parallel processes, and because of that deadlocks were avoided.
Event manipulation for Nondeterministic Shared-Memory Programs
/ High-Performance Computing and Networking. 9th International Conference, HPCN Europe 2001, Amsterdam, the Netherlands, June 25–27, 2001, This type of bug is known colloquially as a Heisenbug
In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect ...
, by analogy with the observer effect in quantum mechanics.
See also
* Observer effect (physics)
In physics, the observer effect is the disturbance of an observed system by the act of observation. This is often the result of utilising instruments that, by necessity, alter the state of what they measure in some manner. A common example is c ...
* Observer's paradox
Sources
{{DEFAULTSORT:Probe Effect
Software testing
Debugging