sudo forks and execs the program. sudo also hangs around as the parent of the program waiting on the program and also forwarding signals.
sudo does not forward signals when the originator comes from the same process group. recently, there has been a change where it will
forward signals as long as sudo or the command is not the group leader (https://www.sudo.ws/repos/sudo/rev/d1bf60eac57f)
for us, this means that calling kill from this node process doesn't work since it's in the same group (and ubuntu 22 doesn't have the above fix).
the workaround is to invoke a kill from a different process group and this is done by starting detached
another idea is: use "ps --pid cp.pid -o pid=" to get the pid of the command and then send it signal directly
see also: https://dxuuu.xyz/sudo.html
the gzip takes a lot of cpu processing and hogs the CPU. With a nice
level, we give other things higher priority.
An alternate idea that was explored was to use cpulimit. This is to
send SIGSTOP and SIGCONT periodically but this will not make use of the
CPU if it's idle (unlike nice).
Another idea is to use cgroups, but it's not clear how to use it with
the dynamic setup we have.
part of #691
If it fails, it's really OK. Maybe we will have a button to remove
images.
This goes further into step of webadmin always staying up and not
crashing/erroring for cosmetic issues.
it seems that scaling down addons can fail at times. this can happen
if the kernel is busy swapping things etc. so, we do not block the
platform startup for this operation.
Nov 13 05:20:00 localhost dockerd[28831]: time="2018-11-13T05:20:00.365056059Z" level=error msg="Handler for POST /v1.37/containers/mongodb/update returned error: Cannot update container 6532d4a923ce9f10303f2e2aa7f03c35383864f44f3db6abd5c58da3c1a7702f: docker-runc did not terminate sucessfully: failed to write 419430400 to memory.memsw.limit_in_bytes: write /sys/fs/cgroup/memory/docker/6532d4a923ce9f10303f2e2aa7f03c35383864f44f3db6abd5c58da3c1a7702f/memory.memsw.limit_in_bytes: device or resource busy\n: unknown"
Nov 13 05:20:00 localhost node[5486]: box:shell updatemongodb (stderr): Error response from daemon: Cannot update container 6532d4a923ce9f10303f2e2aa7f03c35383864f44f3db6abd5c58da3c1a7702f: docker-runc did not terminate sucessfully: failed to write 419430400 to memory.memsw.limit_in_bytes: write /sys/fs/cgroup/memory/docker/6532d4a923ce9f10303f2e2aa7f03c35383864f44f3db6abd5c58da3c1a7702f/memory.memsw.limit_in_bytes: device or resource busy
