Rx: Treating Bugs As Allergies— A Safe Method to Survive Software Failures

Ref: Rx: Treating Bugs As Allergies— A Safe Method to Survive Software Failures

• Software failure recovery to make the softwares more available
• Makes use of Checkpointing and Rollback to revert to an older state
• Then makes some environmental changes and continues the execution of the application.
  • If none of the changes work, it goes back one more checkpoint and retries
• Components
  • Proxy: Separates client and server interactions and helps in the saving and replay of requests upon re-execution.
  • Sensors: Identifies when there is an error in the application using exceptions, interrupts etc.
  • Checkpointing and Rollback
    • Based on: Flashback
    • Deletes oldest checkpoint based on stratergies.
  • Environmental wrappers: For modifying environment during re-execution
    • Memory allocation wrappers: eg: zero fill, add padding
    • Scheduling wrapper to change the unit of time for scheduling
    • User request dropping
  • Control unit: Coordinates with all the components
    • Also provides useful information for the programmer to diagnose and fix errors.
• Tested on Squid, Apache, CVS, MySQL