Probe effect
Probe effect is 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, oscilloscope, or other testing device via a test probe, small amounts of capacitance, resistance, or inductance 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 of parallel computer programs, sometimes failures are not present when debugger's code is attached to the program. This is because additional code changed timing of the execution of parallel processes, and because of that deadlocks were avoided. This type of bug is known colloquially as a Heisenbug, by analogy with the observer effect in quantum mechanics.
