Process Restart on HP-UX

[Daniel Pulido]

Is there an operating system feature on HP-UX that allows you to stop (or pause really) a process and restart it at a later date, like the CPR (Checkpont and Restart) option in IRIX; where the "state" of the process is written out to a file and then that file can be used, with the restart command, to resend the process when ever the user chooses.

Thanks

Dan

[James R. Ferguson]

Daniel:

You can issue a SIGSTOP & SIGCONT signals with the kill command if that helps.

I am familar with some of the mechanisms to which you refer from other operating systems, but I'm not sure further, here.

...JRF...

[Patrick Wessel]

The answer from the "HP-UX Process Management White Paper"is:

When a program starts up a process, the kernel allocates a structure for it from the process table. The process is now in idle state, waiting for system resources. Once it acquires the resource, the process is linked onto a run queue and made runnable. When the process acquires a time-slice, it runs, switching as necessary between kernel mode and user mode. If a running process receives a SIGSTOP signal (as with control-Z in vi) or is being traced, it enters a stop state. On receiving a SIGCONT signal, the process returns to a run queue (in-core, runnable). If a running process must wait for a resource (such as a semaphore or completion of I/O), the process goes on a sleep queue (sleep state) until getting the resource, at which time the process wakes up and is put on a run queue (in-core, runnable). A sleeping process might also be swapped out, in which case, when it receives its resource (or wakeup signal) the process might be made runnable, but remain swapped out. The process is swapped in and is put on a run queue. Once a process ends, it exits into a zombie state.