Question
LabVIEW Restored Source and Compiled Code Cache: Synchronization After Backup Recovery
Ira Orbit
0 reputation · 11 Aug 2020, 19:20 UTC
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0 reputation · 11 Aug 2020, 19:20 UTC
When a LabVIEW project is restored from a file-system backup, the .vi, .lvlib, and .lvproj files are recovered as source text, but the compiled code cache and any previously generated executables are not necessarily part of that backup. A key uncertainty is how LabVIEW determines whether the restored source matches the cached compiled code. The 'Verify VI' utility can check for syntax errors, but it does not address cache consistency. Build specifications are restored as text, yet the executables they describe must be regenerated.
The question is what triggers a recompile after restoration—does LabVIEW compare file hashes, timestamps, or rely on manual action? And how can a user confirm that the restored project's build output corresponds exactly to the restored source, especially when the cache is missing or stale?
Specific questions:
26525 reputation · 12 Aug 2020, 02:54 UTC
When a LabVIEW project is restored from a file-system backup, the .vi, .lvlib, and .lvproj files are recovered as source text, but the compiled code cache and any previously generated executables are not necessarily part of that backup. This creates a synchronization gap between the source code and the binary representation used for execution.
There is no single 'Clear All Cache' button within the project interface. However, you can force a clean state by manually removing the local cache directories. This ensures that every VI is re-evaluated against the restored source.
labview%APDATA%\National Instruments\LabVIEW\Cache.The 'Find Missing Items' tool scans the project for broken references to external libraries. If a library was restored to a different path than the original, the tool will flag these references as broken. It does not interact directly with the compiled cache; it operates at the file-system reference level. If paths have changed, you must manually remap the libraries before the cache can be successfully synchronized again.
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26,525 reputation · 11 Aug 2020, 22:32 UTC
While clearing the cache directory forces a fresh compilation, it is important to note that LabVIEW's reliance on timestamps can be problematic if the backup restoration process resets file dates to the time of recovery rather than the time of original modification. This can lead to a state where the source appears "newer" than the cache, but the actual logic is older.
To confirm that the restored project's build output corresponds exactly to the source without relying solely on timestamps, consider these steps:
Note: Deleting the cache will significantly increase the initial load time of the project as every VI must be recompiled upon first access.