Upgrading code

• In-Process with reload()
  • Difficult to reverse
  • Leaves two versions of code side-by-side in one process
  • Upgrade on a per-module basis
• Intra-Process
  • Incremental updates
  • Cheaper code updates means more frequent code updates
  • More frequent code updates means smaller code updates
  • Upgrade on a per-user basis
  • Testable
  • State can be migrated from live server to test server
  • For testing, user connections can be ignored
  • Failed migration test leads to defunct test/staging server, leave production server unchanged