On 2018-10-18 18:08, Erik Joelsson wrote:
Hello Aleksey,
We very deliberately added the automatic niceness for a better general
user experience. This was back when build-infra was new and we started
pushing the parallelism of the build to where the UIs of our
development systems became annoyingly slow and sluggish when building.
So, I would be very against removing it completely, but I certainly
think it should be possible to opt out. We should never force such a
behavior on an unwilling user. My only defense is that this was done
so early so we probably didn't think about it. If you would like to
provide a patch adding a configure arg for disabling it, it would
certainly be welcome.
An alternative, I suspect, is to lower the value that is added to the
niceness, e.g. using "nice -n5" or even just "nice -n1". This sounds
like it should help with your particular case, and I still think it
would solve our original problem, that developer's workstations should
not be unresponsive while building.
I was about to suggest that you could achieve this by overriding NICE in
the configure command line, by e.g. configure NICE="/usr/bin/nice -n0"
(I presume -n0 is a no-op), but it turned out that this did not work! :(
I opened JDK-8213239 for this, but for the moment, that's not a usable
workaround...
/Magnus
/Erik
On 2018-10-18 01:08, Aleksey Shipilev wrote:
Hi,
Is there any specific user story behind "nice"-ing the compilation
jobs from within the build system?
It unfortunately clashes with priority budgeting. For example, my
build server is used by me doing
adhoc builds, automatic builds and some background tasks. The
automatic build user has priority 10
set in /etc/security/limits.conf. The background user has priority 20
set in limits.conf. In theory,
it sounds good: it would get all the CPU ad-hoc builds want, then
give CPU to automatic build jobs,
then to background jobs.
But then the build nice-s the compilation jobs, which drops its
priority down to the priority of
background jobs:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
25966 backgro+ 39 19 808872 460772 2440 R 97.0 1.4 4181:54 R
25968 backgro+ 39 19 808872 460588 2340 R 97.0 1.4 4181:17 R
25965 backgro+ 39 19 808872 460864 2680 R 93.4 1.4 4180:29 R
30998 buildbot 39 19 6688224 1.050g 20000 S 64.8 3.4 4:58.52 java
27518 buildbot 39 19 2915828 110884 21740 S 47.0 0.3 0:02.57 javac
26802 buildbot 39 19 290900 264792 17392 R 38.2 0.8 0:05.48
cc1plus
27486 buildbot 39 19 200296 171792 18440 R 30.6 0.5 0:01.96
cc1plus
...which wrecks up this story. Maybe the better solution in build
system is to avoid nice-ing at
all, and require users who need it to invoke "nice -n ... make ..."?
Or maybe at least have the knob
that disables automatic niceness?
Thanks,
-Aleksey
