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looker: Update heap size calculation for cgroups #23

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looker: Update heap size calculation for cgroups #23

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24 changes: 19 additions & 5 deletions startup_scripts/looker
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Original file line number Diff line number Diff line change
@@ -1,11 +1,25 @@
#!/bin/sh

cd $HOME/looker
# set your java memory- there should be over 1.5G of system memory
# left to run the OS
MEM=`cat /proc/meminfo | grep MemTotal | awk '{print $2}'`
JM=`expr $MEM \* 6 / 10`
JAVAMEM="${JM}k"
# set your java memory- heap set to 60% of max OS or if there's a cgroup limit
memTotalKb="$(awk -F ':? +' '$1 == "MemTotal" { print $2; exit }' /proc/meminfo)"
if [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
# "18446744073709551615" is a valid value for "memory.limit_in_bytes", which is too big for Bash math to handle
# "$(( 18446744073709551615 / 1024 ))" = 0; "$(( 18446744073709551615 * 40 / 100 ))" = 0
memLimitKb="$(awk -v totKb="$memTotalKb" '{
limB = $0;
limKb = limB / 1024;
if (!totKb || limKb < totKb) {
printf "%.0f\n", limKb;
}
}' /sys/fs/cgroup/memory/memory.limit_in_bytes)"
else
memLimitKb="$memTotalKb"
fi
JAVAMEM="$(awk -v limKb="$memLimitKb" 'BEGIN{
limKb = limKb * 6 / 10;
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I kept this math the same, but using 60% feels a bit wrong to me, if your goal is to basically be limKb = limKb - (1024 * 1024 * 1.5);

So let me know if you want me to accommodate for that instead, I just didn't wanna change behavior.

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It seems imo, if we have a cgroup, we can set the limit to exactly the cgroup (maybe subtract a few MB to keep some breathing room), and apply the 60% or some -1.5GB of the value comes from the whole system's memory. If we're running within a container, I'm not sure why we'd need to have that much breathing room.

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@mconigliaro mconigliaro Mar 1, 2022 •
edited
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The JVM has support for containers now, so you can just use something like: -XX:MaxRAMPercentagerather=90.0.

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This is probably irrelevant now since as you mentioned the JVM now supports automatically setting the heap size when it detects it is running in a container.

However, when running on Ubuntu 20.04.5 LTS the /sys/fs/cgroup/memory/memory.limit_in_bytes file seems to have been replaced by /sys/fs/cgroup/memory.max.

For me, running this in docker, the memory.max file stores the max memory limit in bytes.

$ cat /sys/fs/cgroup/memory.max
4294967296

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Excuse my ignorance of cgroups, this seems to be a platform issue, when running Docker Desktop on MacOS /sys/fs/cgroup/memory.max is the file but when running on a Linux node the file was /sys/fs/cgroup/memory/memory.limit_in_bytes

printf "%.0f\n", limKb;
}')k"
METAMEM="800m"

# Extra Java startup args and Looker startup args. These can also be set in
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