Spot instances are the equivalent of stopping an instance while it's running. You get a signal (30 seconds prior for Google, 2 mins for AWS) and you are free to

Spot instances are the equivalent of stopping an instance while it's running. You get a signal (30 seconds prior for Google, 2 mins for AWS) and you are free to try and handoff the work to a different machine in your cluster . Basically this is good for running short jobs and not long running ones. If you have a service that process chunks of data from a queue it's probably the ideal scenario. In practice, with AWS your instances don't get killed that often. Some in the comments are claiming months but I was using mine with AWS Batch and they usually lived 1-2 weeks.