SIGXCPU
The CPU limit burst — a warning before the final cut.
Processes can carry a CPU-time ceiling — ulimit -t, RLIMIT_CPU. On crossing the soft limit, the kernel rings this bell; it is the chance to save the work and leave with dignity.
Whoever catches the warning and keeps burning CPU discovers the contract's second half: at the hard limit comes SIGKILL — and that one doesn't warn, it executes. Batch queues use the pair as a fence.
$ ulimit -t 5
$ ./laco-guloso
CPU time limit exceeded (core dumped)