Plesk vs. Classic Windows Hosting: Software Engineering Differences
Our Plesk shared hosting accounts handle the following software engineering features differently than our free Windows hosting accounts:
Concurrent file writes to the same file in multiple sessions or concurrent threads are not supported. Example of affected resources: File-based databases and cross session log files (these issues are exaggerated in a Web Hosting environment due to additional volume).
Storing data within the Application namespace and depending on multiple concurrent sessions accessing accurate data for the entire application is not supported.
Static Classes where sessions across the Website (application) must have concurrent access to accurate data.