US Patent 11663150 Fault tolerant system

A fault tolerant system includes a primary virtual machine and a secondary virtual machine. The primary virtual machine includes a synchronizing information generator and a first interrupt blocker. The synchronizing information generator executes bytecode and outputs synchronizing information based on information related to the executed bytecode. The first interrupt blocker blocks an interrupt inputted from an external location. The secondary virtual machine includes a synchronous execution unit that executes the bytecode based on the synchronizing information and a second interrupt blocker that blocks the interrupt. When the interrupt is acquired, the synchronizing information generator executes the bytecode based on the interrupt. The first interrupt blocker outputs the interrupt to the synchronizing information generator when the interrupt is inputted during execution of an instruction, included in the bytecode, to accept the interrupt.