How long does subVI stay in memory

Question

Hi,
      I would like to know how long does a subvi stay in memory? If it is not used anymore will LabVIEW automatically close it? Thanks!
      Tom
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Answer 1

Overall, we don't have enough information to fully answer the question, because the question is not very specific.
For example:
if the subVI is called dynamically, it probably can leave memory once it is closed.
If the subVI is reentrant, It can have multiple instances in memory.
To have a subVI in memory is typically irrelevant in terms of the memory the code alone occupies. More serious is the amount of data structures allocated by the subVI. Here we have some tools, e.g. the "request deallocation" primitive. This can be useful if a subVI is called only once, and then never again, but needs gigantic data structures. Typically, subVIs are called multiple times with similar data structures, so it would be a mistake to constantly deallocate, only to reallocate a few nanoseconds later.
As Smercurio_fc already mentioned, another important question for performance tuning is if the front panel is in memory or not. A subVI that does not need to have the FP in memory executes often much faster and takes less memory. It is thus important not to have the FP of subVIs open unless there is a need for interaction. Certain coding habits (e.g. use of some invoke nodes or some property nodes) also force the FP in memory, even if the FP is not shown. This is documented in the help for each method/property so it is important to avoid these if they are not really needed.
 In summary, it would be interesting to know what exact concerns the OP had when he asked " I would like to know how long does a subvi stay in memory?".
There has to be more to the question...
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