On Feb 15, 2018, at 12:52 PM, Volker Simonis <volker.simo...@gmail.com>
wrote:
Sounds cool!
Is this JEP only about providing the corresponding API or also about
using it internally (within HotSpot and class library) to better adopt
to environment the JVM is running in?
Thanks Volker.
I integrated JDK-8146115 into JDK 10 which allows Hotspot to adapt to the
container it’s running in. The configuration that is examined includes
memory limits,
cpu count including cpu shares and quotas.
This JEP’s main focus is to provide an internal API that can be used by
JDK tools
such as JFR and JMX to export container statistics and configuration
data. This JEP
does not include the JFR and JMX implementations. They will hopefully
follow shortly after.
Bob.
Either way, looking forward to see (and test) the first implementation
bits!
Regards,
Volker
On Thu, Feb 15, 2018 at 6:07 PM, Bob Vandette <bob.vande...@oracle.com>
wrote:
I’d like to re-propose the following JEP that will enhance the Java
runtime to be more container aware.
This will add an Internal Java API that will provide container specific
statistics. Some of the initial goals
of the previous JEP proposal has been integrated into JDK 10 under an
RFE (JDK-8146115).
This JEP is now focused on providing a Java API that exports Container
runtime configuration and metrics.
Since the scope of this JEP have changed, I’m re-submitting it for
comment and endorsement.
JEP Issue:
https://bugs.openjdk.java.net/browse/JDK-8182070
Here’s a Text dump of the JEP contents for your convenience:
Summary
-------
Container aware Java runtime
Goals
-----
Provide an internal API that can be used to extract container specific
configuration and runtime statistics. This JEP will only support Docker on
Linux-x64 although the design should be flexible enough to allow support
for other platforms and container technologies. The initial focus will be
on Linux cgroups technology so that we will be able to easily support other
container technologies running on Linux in addition to Docker.
Non-Goals
---------
It is not a goal of this JEP to support any platform other than Docker
container technology running on Linux x64.
Success Metrics
---------------
Success will be measured by the improvement in information that will be
available to tools which visualize resource usage of containers that are
running Java processes.
Motivation
----------
Container technology is becoming more and more prevalent in Cloud based
applications. The Cloud Serverless application programming model motivates
developers to split large monolithic applications into 100s of smaller
pieces each running in thier own container. This move increases the
importance of the observability of each running container process. Adding
the proposed set of APIs will allow more details related to each container
process to be made available to external tools thereby improving the
observability.
Description
-----------
This enhancement will be made up of the following work items:
A. Detecting if Java is running in a container.
The Java runtime, as well as any tests that we might write for this
feature, will need to be able to detect that the current Java process is
running in a container. A new API will be made available for this purpose.
B. Exposing container resource limits, configuration and runtime
statistics.
There are several configuration options and limits that can be imposed
upon a running container. Not all of these
are important to a running Java process. We clearly want to be able to
detect how many CPUs have been allocated to our process along with the
maximum amount of memory that the process has been allocated but there are
other options that we might want to base runtime decisions on.
In addition, since Container typically impose limits on system
resources, they also provide the ability to easily access the amount of
consumption of these resources. The goal is to provide this information in
addition to the configuration data.
I propose adding a new jdk.internal.Platform class that will allow
access to this information.
Here are some of the types of configuration and consumption statistics
that would be made available:
isContainerized
Memory Limit
Total Memory Limit
Soft Memory Limit
Max Memory Usage
Current Memory Usage
Maximum Kernel Memory
CPU Shares
CPU Period
CPU Quota
Number of CPUs
CPU Sets
CPU Set Memory Nodes
CPU Usage
CPU Usage Per CPU
Block I/O Weight
Block I/O Device Weight
Device I/O Read Rate
Device I/O Write Rate
OOM Kill Enabled
OOM Score Adjustment
Memory Swappiness
Shared Memory Size
Alternatives
------------
There are a few existing tools available to extract some of the same
container statistics. These tools could be used instead. The benefit of
providing a core Java internal API is that this information can be expose
by current Java serviceability tools such as JMX and JFR along side other
JVM specific information.
Testing
-------
Docker/container specific tests should be added in order to validate
the functionality being provided with this JEP.
Risks and Assumptions
---------------------
Docker is currently based on cgroups v1. Cgroups v2 is also available
but is incomplete and not yet supported by Docker. It's possible that v2
could replace v1 in an incompatible way rendering this work unusable until
it is upgraded.
Other alternative container technologies based on hypervisors are being
developed that could replace the use of cgroups for container isloation.
Dependencies
-----------
None at this time.
