Abstract. Infinite loops can make applications unresponsive. Potential problems include lost work or output, denied access to application functionality, and a lack of responses to urgent events. We present Jolt, a novel system for dynamically detecting and escaping infinite loops. At the user's request, Jolt attaches to an application to monitor its progress. Specifically, Jolt records the program state at the start of each loop iteration. If two consecutive loop iterations produce the same state, Jolt reports to the user that the application is in an infinite loop. At the user's option, Jolt can then transfer control to a statement following the loop, thereby allowing the application to escape the infinite loop and ideally continue its productive execution. The immediate goal is to enable the application to execute long enough to save any pending work, finish any in-progress computations, or respond to any urgent events.We evaluated Jolt by applying it to detect and escape eight infinite loops in five benchmark applications. Jolt was able to detect seven of the eight infinite loops (the eighth changes the state on every iteration). We also evaluated the effect of escaping an infinite loop as an alternative to terminating the application. In all of our benchmark applications, escaping an infinite loop produced a more useful output than terminating the application. Finally, we evaluated how well escaping from an infinite loop approximated the correction that the developers later made to the application. For two out of our eight loops, escaping the infinite loop produced the same output as the corrected version of the application.

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We present Bolt, a novel system for escaping from infinite and long-running loops. Directed by a user, Bolt can attach to a running process and determine if the program is executing an infinite loop. If so, Bolt can deploy multiple strategies to escape the loop, restore the responsiveness of the program, and enable the program to deliver useful output. Bolt operates on stripped x86 and x64 binaries, dynamically attaches and detaches to and from the program as needed, and dynamically detects loops and creates program state checkpoints to enable exploration of different escape strategies. Bolt can detect and escape from loops in off-the-shelf software, without available source code, and with no overhead in standard production use.