CODEWITHSUNDEEP
javajvmjvm-argumentsopenjdk-11
reikje
reikje

Reputation: 3064

How do you limit non-heap size on Open JDK 11

we are running openjdk:11-slim based docker containers in AWS. We usually use two instance types. One with 1G, the other with 2G of available memory. On the 1G instances, I have started to constraint the heap size using these args: -XX:MaxRAM=1g -XX:MaxRAMPercentage=30

I would like to constrain non-heap as well. It is a Spring Boot application and in Spring Boot Admin it currently looks like this (running default):

enter image description here

As you can see, 1.33 GB Max wouldn't even work because there is only 1G of total memory. Ideally, the non-heap should be constraint to stay within 30% as well. Which JVM args can I use to size the non-heap memory?

I have investigated a little bit and on this instance, about 30% of 1G total RAM are already used for non application related processes (third column is the percentage of total memory).

3663 root      4.6 /usr/bin/python2.7 /usr/bin/aws logs push --config-file /etc/awslogs/awslogs.conf --additional-configs-dir /etc/awslogs/config
 3430 root      4.1 /usr/bin/dockerd --storage-driver devicemapper --storage-opt dm.thinpooldev=/dev/mapper/docker-docker--pool --storage-opt dm.use_deferred_removal=true --storage-opt dm.use_deferred_deletion=true --storage-opt dm.fs=ext4 --storage-opt dm.basesize=100G
 2949 healthd   3.5 puma 2.11.1 (tcp://127.0.0.1:22221) [healthd]
 3021 root      2.6 /usr/bin/python2.7 /opt/aws/bin/cfn-hup
 3437 root      2.2 containerd --config /var/run/docker/containerd/containerd.toml --log-level info
 4867 root      2.1 docker logs -f f82ef403ef45
 4831 root      2.0 docker wait f82ef403ef45
 3501 root      1.9 docker events
 3322 root      1.7 /sbin/dmeventd
16976 root      0.7 sshd: ec2-user [priv]
 2280 root      0.6 /usr/bin/amazon-ssm-agent

Upvotes: 3

Views: 10843

Answers (1)

user3453226
user3453226

Reputation:

You cannot constraint off-heap memory, otherwise the application would crash. When direct memory is allocated, it is always needed, so denying it is the same as OutOfMemoryError.

You can limit metaspace size with -XX:MaxMetaspaceSize=.

You can reduce the amount of memory used by the JIT compiler to store compiled methods, therefore potentially reducing compilation, with -XX:ReservedCodeCacheSize=.

Upvotes: 6

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