Systems and methods are described herein for job execution using system critical threads. An in-memory database system having pages loaded into a memory and having associated physical disk storage generates a safety critical thread pool. The safety critical thread pool has one or more safety critical threads associated with flushing the pages to the physical disk storage. Execution of the one or more safety critical threads is initiated within the safety critical thread pool. A job request to access data stored within the physical disk storage is received. Utilization levels of the one or more safety critical threads are monitored. Execution of the job request is permitted based on the utilization levels associated with the one or more safety critical threads.