Ubuntu – How to prevent a process from being killed

niceprocess

Is there anyway to prevent a process from being killed no matter what? I know about nice but I'm not sure if giving a task such as a long running memory-intensive rake task the highest priority will prevent it from being killed off:

nice -n -20 rake xyz

Edit: The original poster most likely wants it to be high priority even if the server is low on resources as well, so much so that other processes get killed first.

Best Answer

Why would it be killed off?

Because it's not automatic that something is killed. Once you answer that, and explain why something would be selected for destruction, you might be able to come up with a solution.

Given you're talking about Rails' rake command, I'm guessing that this is a process running on a server. That you're worried about it being killed suggests it's being killed by the server host for using too many resources. In cases like this, there aren't (nor should there be) ways of stopping your process for being killed.

If you have a resource-expensive task, buy more resources. Use your own server time. Or come to an arrangement with the host that allows you to run it on their dime.

Related Solutions

Ubuntu – How to change niceness of process by name

If you have only one java instance running, simply:

renice -n 5 -p $(pgrep ^java$)

$(pgrep ^java$): command substitution; bash replaces this with the output of pgrep ^java$; pgrep ^java$ returns the list of PIDs of the processes whose name matches the regular expression ^java$, which matches all processes whose name is exactly java

If you have multiple java instances running:

for p in $(pgrep ^java$); do renice -n 5 -p $p; done

for p in $(pgrep ^java$); do renice -n 5 -p $p; done: almost the same as above; $(pgrep ^java$) is a command substitution; bash replaces this with the output of pgrep ^java$; pgrep ^java$ returns the list of PIDs of the processes whose name matches the regular expression ^java$, which matches all processes whose name is exactly java; this is expanded into the for loop, which assigns a new line of the output of pgrep ^java$ to the variable $p and runs renice -n 5 -p $p at each iteration until the output of pgrep ^java$ is consumed

Ubuntu – Process ‘niceness’ vs. ‘priority’

Nice value is a user-space and priority PR is the process's actual priority that use by Linux kernel. In linux system priorities are 0 to 139 in which 0 to 99 for real time and 100 to 139 for users. nice value range is -20 to +19 where -20 is highest, 0 default and +19 is lowest. relation between nice value and priority is :

PR = 20 + NI

so , the value of PR = 20 + (-20 to +19) is 0 to 39 that maps 100 to 139.

According to top manual:

PR -- Priority The scheduling priority of the task. If you see 'rt' in this field, it means the task is running under 'real time' scheduling priority.

NI is nice value of task.

NI -- Nice Value The nice value of the task. A negative nice value means higher priority, whereas a positive nice value means lower priority.Zero in this field simply means priority will not be adjusted in determining a task's dispatch-ability

Edit: By default when a program is launched in Linux, it gets launched with the priority of '0'. However you can change the priority of your programs by either of the following methods.

You can launch a program with your required priority using
```
nice -n nice_value program_name
```
you can also change the priority of an already running process using
```
renice -n nice_value -p process_id
```

Best Answer

Related Solutions

Ubuntu – How to change niceness of process by name

Ubuntu – Process ‘niceness’ vs. ‘priority’

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