Presto is not releasing the memory

[hmanju2k7]

We are using 0.234.1 version of Presto DB.

The memory utilization of the VM is initially 7% when no queries are running, after we run some queries, thr VM memory utilization goes up to 40%

But then when we are not running any queries, memory is not getting released and stays at 40% instead of coming back to 7%.

The memory becomes free only after we restart the Presto server.

Because of this we are not able to auto scale down the Presto worker nodes based on memory utilization.

Any help or suggestions would be really helpful.

[bing0109]

i got the same problem in 0.245.1

[rongrong]

@mbasmanova @bhasudha Is this something you guys can take a look into?

[rohanpednekar]

@hmanju2k7 can you share your JVM flags for presto config?

[929359291]

I have the same problem, this is my jvm.config，please help me, thanks, @rohanpednekar

-server
-Xmx28G
-XX:-UseBiasedLocking
-XX:+UseG1GC
-XX:+ExplicitGCInvokesConcurrent
-XX:+HeapDumpOnOutOfMemoryError
-XX:+UseGCOverheadLimit
-XX:+ExitOnOutOfMemoryError
-XX:ReservedCodeCacheSize=512M

config.properties：
coordinator emr-default
discovery-server.enabled emr-default
discovery.uri
http-server.http.port 9000
node-scheduler.include-coordinator emr-default
query.max-memory 24GB
query.max-memory-per-node 8GB
query.max-stage-count 700
query.max-total-memory-per-node 12GB
task.max-worker-threads 4

[929359291]

please help me, please @-@

[hetu18274506280]

@hmanju2k7 @rongrong @rohanpednekar @929359291 @mbasmanova How do you solve this problem

[mbasmanova]

Folks, I'm not sure I understand the question here. Java, unlike C++, does not guarantee that memory is released when not used anymore.

Because of this we are not able to auto scale down the Presto worker nodes based on memory utilization.

Presto reports the actual memory usage of the queries. Can you use this information for auto scaling?

[mbasmanova]

See https://stackoverflow.com/questions/30458195/does-gc-release-back-memory-to-os for relevant discussion.

[929359291]

有关相关讨论，请参阅https://stackoverflow.com/questions/30458195/does-gc-release-back-memory-to-os。

thanks