What are the challenges to using Java for serverless functions and what features of the JDK and other tools are available to address them?

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Serverless Java
Shaun Smith
Director of Product Management
Oracle Cloud Infrastructure—Serverless
@shaunMsmith
May 18, 2019
Challenges and Triumphs

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Serverless

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Serverless is an abstraction of infrastructure and its
operations including provisioning, scaling, patching, etc.
FaaS (Functions-as-a-Service) is the compute
component in a serverless platform
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Example Java Function
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Serverless Today
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Interest in Serverless
Source: Google Trends

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Source: https://jaxenter.com/technologies-dominate-2019-poll-152470.html

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Peak of Inflated Expectations
Plateau of Productivity
Slope of Enlightenment
Trough of Disillusionment
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Serverless Java?
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https://blog.github.com/2018-11-15-state-of-the-octoverse-top-programming-languages/
Top programming languages by contributors as of September 30, 2018

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New Relic: 9.1% of functions are Java 8!?
https://blog.newrelic.com
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Serverless.com: 6.1% of all functions are Java!?
https://serverless.com/blog/2018-serverless-community-survey-huge-growth-usage/
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Serveless.com, Large Companies > 1000: 14.9% Java
https://serverless.com/blog/2018-serverless-community-survey-huge-growth-usage/
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And the Trend isn’t Great
https://serverless.com/blog/serverless-by-the-numbers-2018-data-report/
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http://redmonk.com/jgovernor/2016/10/12/when-web-companies-grow-up-they-turn-into-java-shops
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Why isn’t Java popular for Functions?
• FaaS seen as a scripting platform for the web?
• Doesn't fit normal Java development patterns?
• Java not suitable for short-lived “apps”?
• Not supported?
–Google Cloud Functions—N/A
–AWS Lambda—Java support added June 2015
–Oracle Functions—Limited Availability Dec. 2018
–Azure Functions—Java 8 GA on Feb 2019
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Blueprint for Serverless Java
• “Plain old Java”
• Established toolchains
• Ability to build complex applications
• Low latency/high performance
• Java ecosystem
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www.fnproject.io
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• Open-source, Container Naive, Serverless Plajorm
• Apache v2 licence
• Run anywhere - Cloud / Datacenter / Laptop
• Fn ♥
• Funcions are containers
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Fn Java Function Development Kit (FDK)
• Docker Images
–A build image for repeatable builds
–An optimized runtime image
• JUnit Test Harness
• Maven support
• Input/output coercion
• Flow
• …
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Java Functions Demo!

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Blueprint for Serverless Java
• “Plain old Java” ✓
• Established toolchains ✓
• Ability to build complex applications
• Low latency/high performance
• JVM ecosystem
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Fn Flow

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Fn Flow
• Provides rich concurrency primitives including fork-join, chaining, delays
and error handling
• Java support based on Java 8 CompletableFuture API
• Build reliable and scalable FaaS applications
For long-running, reliable, scalable functions

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Fn Flow Demo

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http://microservices.io/patterns/data/saga.html

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Fn Flow Demo!

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Blueprints for Serverless Java
• “Plain old Java” ✓
• Wide choice of good tooling ✓
• Ability to build complex applications ✓
• Low latency/high performance
• Rich JVM ecosystem
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Low Latency/High Performance – Java in Containers
What do we want containerized Java applications to do?
–Respect resource constraints
–Start fast
–Run fast
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Container Friendly Java – Respecting Resource Constraints
• JDK-8179498: attach in linux should be relaive
to /proc/pid/root and namespace aware as jcmd, jstack, etc. fail to
arach (resolved in JDK 10)
• JDK-8193710: jcmd -l and jps commands do not list Java processes
running in Docker containers (resolved in JDK 11)
• JDK-8203357: Container Metrics (resolved in JDK 11.0.1)
• JEP 318: Epsilon: A No-Op Garbage Collector (Experimental in JDK 11)
• …
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Fast Startup – Moving Costs to Build-Time
1. Class Data Sharing (CDS)
– Avoid parsing JDK classes on start
2. Application CDS
– Avoid parsing App classes on start
3. AOT compilation
– Compile App classes to native .so libraries (experimental)
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Fast Startup – Small Container Images
Small JVM container images means faster startup by reducing:
–Image to host transfer time
–Docker Copy on Write (COW) cache creation
–Docker Overlay FS setup
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Fast Startup — Building Smaller Java Container Images
1. Use jlink to remove unused core libraries
2. Start with small base images
3. GraaVM native image - compile Java to a static binary
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Fast Startup — Small Base Images
Security-oriented, lightweight Linux distribution
with 4MB base image
Lightweight, fast, simple, free, C standard library
implementation
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Reduce OS layer size
Project Portola’s goal is to run the JVM on Alpine Linux/Musl

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Fast Startup — Smaller Java Applications
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Reduce Java Runtime layer size - jlink
Modules JLink flags Mb
JDK 12 Whole JDK! 318.7
openjdk:11-jre-slim 11 (default) NB: openjdk:12-jre-slim not yet available! 217
JRE 12 all (explicit) --add-module $(java --list-modules) 168.3 100.0%
+ --no-header-files --no-man-pages --strip-debug 143.0 85.0%
+ --compress=1 107.8 64.1%
+ --compress=2 83.7 49.7%
Custom JRE 12 base, logging --add-module $(jdeps --print-module-deps func.jar) 47.4 28.2% 100.0%
+ --no-header-files --no-man-pages --strip-debug 41.6 24.7% 87.8%
+ --compress=2 32.0 19.0% 67.5%
OpenJDK (build 12-ea+29) - alpine:3.9 x86_64
318 Mb 168 Mb 47 Mb 32 Mb

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Fast Startup — Smaller Java Applications
• GraalVM compiles Java source to a single native binary
• Tiny image sizes
• Low VM overhead
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GraalVM
Functions Demo!

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Blueprint for Serverless Java
• “Plain old Java” ✓
• Wide choice of good tooling ✓
• Ability to build complex applications ✓
• Low latency/high performance ✓
• Rich JVM ecosystem ✓
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Serverless Java?

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Serverless Java? Absolutely!

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Shaun Smith
fnproject.io
@shaunMsmith
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Thank you!

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