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Fault Injection

Process Killer Experiment

The Process Killer experiment kills targeted processes over a supplied interval throughout the length of the experiment.

When targeting processes with the --process argument, you can pass a regular expression, which matches processes in the same way that pgrep(1) does, or you can pass a specific Process ID (PID). When passing a regular expression, Gremlin will only match on the process name (arg0) unless --full is also supplied.

Terminating PID 1

PID 1 is most commonly reserved for the init process. On hosts, Process Killer does not work for PID 1. Instead, you should use a Shutdown experiment. On container-based systems (e.g. Kubernetes), you can terminate PID 1, which has the same effect as running a Shutdown experiment.

The only exception is if you want to repeatedly terminate a container process, which is only possible with Process Killer. In that case, you would need to run Process Killer on the container host, ensure that the Gremlin agent is deployed with hostPID set to true, and select the container process from the host.


The Process Killer experiment sends the signal supplied by --signal (defaults to KILL) to processes identified by the rest of the supplied arguments.

This experiment requires the KILL capability, which is enabled by default at installation time. See capabilities(7)


Signal-s stringFalseKILL1.8.0The signal to send to target processes. Values: [HUP,INT,QUIT,ILL,TRAP,ABRT,FPE,KILL,SEGV,PIPE,ALRM,TERM,USR1,USR2]
Interval-i intFalse11.8.0The number of seconds to delay before kills.
Process-p reg ex or intTrue1.8.0The process name to match (allows regex) or the process ID.
Group-g stringFalse1.8.0The group name or ID to match against (name matches only).
User-u stringFalse1.8.0The user name or ID to match against (name matches only).
Newest-nFalseFalse1.8.0If set the newest matching process will be killed (name matches only, cannot be used with -o).
Oldest-oFalseFalse1.8.0If set the oldest matching process will be killed (name matches only, cannot be used with -n).
Exact-eFalseFalse1.8.0If set the match must be exact and not just a substring match (name matches only).
Kill Children-cFalseFalse1.8.0If set the processes children will also be killed.
Full Match-fFalseFalse1.8.0If set the processes name match will occur against the full command line string that the process was launched with.
Length-l intFalse601.8.0The length of the experiment (seconds).