Alibaba Java技术沙龙

主办:GreenTea JUG

赞助: 阿里巴巴

时间: 2018324日下午

地点:  杭州,阿里巴巴西溪园区访客中心-203-N万松书院

时长:  半天

规模:  45

活动介绍:GreenTea JUG以及阿里巴巴JVM Team主办的面向Java用户和JVM研究爱好者的线下交流活动。希望能在Java领域碰撞出更多火花,共建Java生态。


View Fullscreen

GreenTeaJUG 活动 第27期 杭州

时间:2017-11-18 13:30 – 17:00

时间:13:30 – 14:15

时间:14:25 – 15:10
分享人:朱明智 (个推平台研发资深技术专家)

时间:15:20 – 16:00
分享人:刘军(阿里巴巴中间件团队 Dubbo 开发者)

时间:16:10 – 16:55

主题:GreenTeaJUG活动 第27期 杭州


GreenTeaJUG 活动 第26期 北京


时间:2017-04-23 14:30-17:00
地点:北京市海淀区科学院南路2号 融科资讯中心大厦C座9层 红帽软件研发中心


时间: 下午2:40 – 3:20
主题: Java 9新特性
讲师: 杨晓峰 (Oracle, Java核心类库组Lead)
1. Java Platform Module System
– 基本概念
– 分析设计和实现的部分细节
– 典型用例和诊断分析
2. 概要介绍其他虚拟机、类库等方面的新特性
(演示稿 下方预览PDF)

时间:下午3:30 – 4:00
主题: MicroProfile规范子集和实现技术
讲师: 宋志麒 (@KylinSoong, Redhat Teiid核心开发工程师)
1. MicroProfile规范子集介绍及产生背景
2. 目前状态,Feature backlog, release schedule等。
3. Wildfly-Swarm中的实现技术分析

时间:下午4:10 – 4:50
主题: HTTP/2和Servlet4技术分析
讲师: 张建锋 (@shihang-EE守护者 永源中间件共同创始人)
1 HTTP/2
– 特性
– 协议分析
– 二进制帧格式
– 头部压缩/索引表
2 Servlet 4
– 支持HTTP/2的特性
– API增加和改变
3 Web服务器的支持
– Tomcat9
– Jetty 9.4
– Undertow 2
4 可选
– Netty实现HTTP/2技术分析
(演示稿 下方预览PDF)

四,交流讨论 10-30分钟

主题:GreenTeaJUG活动 第26期 北京


一 Java 9新特性
View Fullscreen

二 JavaEE MicroProfile
View Fullscreen

三 HTTP/2和Servlet4技术分析
View Fullscreen

GreenTeaJUG 活动 第25期 杭州

时间:2017-01-21 14:00-17:00
地点:杭州华星路互联网大厦17楼 “冶金炉”会议室,挖财(创业大厦对面)
组织:@JianhaoMo ,@hongjiang_wang

时间:2017-01-21 14:00-17:00
主题:JDK 9: Big Changes to Make Java Smaller
JDK 9 is scheduled for general availability in July 2017.  The biggest new feature for this release of Java is Project Jigsaw that brings modularity to both the core JDK libraries as well as, potentially, application code.

Modularizing the JDK core libraries is not just a simple matter of breaking up the rt.jar file into a number of sections.  The Jigsaw module system allows for encapsulation of packages that developers do not want publicly exposed. Encapsulation of JDK internal APIs will potentially break backwards compatibility for application code that uses these APIs.  This session will explain the practicalities of running applications on JDK 9.

We’ll also look at how you can migrate existing applications to the new module system in a gradual and controlled way to minimize impact on users.

讲师:Simon Ritter, Azul System 布道师,2014年曾作为Oracle布道师在中国巡回演讲,宣讲Java8。

Simon has been in the IT business since 1984 and holds a Bachelor of Science degree in Physics from Brunel University in the U.K. Originally working in the area of UNIX development for AT&T UNIX System Labs and then Novell, Simon moved to Sun in 1996. At this time he started working with Java technology and has spent time working both in Java development and consultancy. Having moved to Oracle as part of the Sun acquisition he now focuses on the core Java platform, Java for client applications and embedded Java. He also continues to develop demonstrations that push the boundaries of Java for applications like gestural interfaces, embedded robot controllers and in-car systems.Follow him on Twitter, @speakjava.

主题:GreenTeaJUG活动 第25期 杭州



Java平台 标准版 故障排查 向导 


2 Diagnostic Tools

3 Troubleshoot Memory Leaks

Part II Debug JVM Issues

5 Troubleshoot System Crashes

6 Troubleshoot Process Hangs and Loops

7 Handle Signals and Exceptions

17 Submit a Bug Report

Part VI Appendix

A Fatal Error Log

C Environment Variables and System Properties

D Command-Line Options

E Summary of Tools in This Release

GreenTeaJUG 活动 第24期 杭州

时间:2016-09-11 14:00-18:00
地点:西湖区古墩路99号 浙商财富中心1号楼蘑菇街 5楼牛津大学会议厅(前台有引导)
组织:@JianhaoMo  、蘑菇街七公

时间:2016-09-11 14:00-15:00
讲师:刘昱接 (吴邪@美丽联合集团)

时间:2016-09-11 15:00-18:00
主题:Cloud Native Java
讲师:Josh Long(@Josh Long

Josh Long 是 Pivotal 公司的 Spring 核心开发者和布道者,他是 Java Champion,5 本书的作者(包括即将出版的 O’Reilly 图书 “Cloud Native Java: Designing Resilient Systems with Spring Boot, Spring Cloud, and Cloud Foundry”),多个知名开源项目(Spring Boot, Spring Integration, Spring Cloud, Activiti 和 Vaadin)的 commiter。

两小时全程 live coding, Josh 带你领略如何基于 Spring Boot & Spring Cloud 开发云端微服务!
组织将大型的目标拆解成小型的、可独立部署的、关注功能点的目标,或者说微服务。为了尽可能缩短各个团队之间沟通的时间,组织慢慢压缩转变,并尽可能地自动化,开发和运维开始做 “devops“ 了,基于云的服务和平台(如 Cloud Foundry)自动化了大量运维工作,改变了管理方式。
然而,高速是伴随危险的,微服务带来了组织必须要面对的架构复杂度。在本次分享中,我们会看一下那些高效的组织如 Ticketmaster 和 Netflix 如何使用 Spring Boot 和 Spring Cloud 来解决这些复杂度。


主题:GreenTeaJUG活动 第24期 杭州


莫简豪 20:26

many people curious about g1. Most apps still use cms. How does g1 perform in real production?

@Martijn Verburg @Monica Beckwith  hope you can give us some infomation

Monica Beckwith 21:01

Sure. If you have any specific use cases I can help. All companies that I worked with, that are able to get to latest JDK 8 release are happy moving to G1… with minimal tuning.

Martijn Verburg 21:34

Kirk and I are presenting our tuning G1 talk at JavaOne. I will post some of our current findings here over the weekend. We have found some usage patterns and edge cases where G1 has some challenges. It also is a good idea to track the open issues on the OpenJDK JIRA labelled with G1. You will see that there are many small fixes and improvements to go.

We would only recommend it for Java 8u91 as there are still JVM crash bugs prior to that

Humongous objects still cause big problems and there are hard limits to reference processing and object copy times depending on the shape of your object graph

ayanamist 22:08

Will g1gc has the ability to do parallel fullgc? Google has a patch for cms to enable parallel fullgc which brings quite a lot enhancement.

e.g. HBase, using BlockCache & MemStore, consumes a lot of heap space, and eventually has a fullgc after not a long time, which affects service availability when heap is large than 100GB. So concurrent fullgc is valuable in this case.

Martijn Verburg 22:18

IIRC the G1 full GC is currently single threaded but they are working on making it parallel. It is not concurrent by design (it has to stop all threads at a safe point). Monica will correct me if I’m wrong 🙂

I’m not yet convinced that G1 works all that well for heaps > 75GB. In *theory* a fully production read Shenandoah will perform better and of course the C4 collector still wins hands down.

That said there are still ~50 G1 bugs and features that they are working on, so I expect it it improve

Monica Beckwith 22:20

I have worked with Hbase and blockcache and memstore with G1 with about 64Gs no full GCs

Martijn Verburg 22:20

Yeah we typically see 64GB heaps for that sort of work

But unless you’re on the latest 8 update we’ve seen instabilities over several weeks of hot running

And of course with G1 the big question is what pause time goals you want 🙂. It’s a great low pause collector but not a low latency low pause collector (if you’re in the high frequency trading business)

Monica’s work on G1 is putting many of us out of a job 😉

One last note before I jump on my next plane. You can still get better extreme low latency out of a well tuned CMS than you can G1. However it takes a lot of work and tuning of many parameters.

This is why RedHat, Google, Twitter, ourselves and a few others will try to maintain CMS for Java 10 – but I think G1 will take over for a majority of applications who want good low pause behaviour with minimal tuning

Monica Beckwith 22:35

Agreed on low latency CMS surpasses G1 because you don’t have any old gen “collection” and you can easily avoid/push off full GCs…

(With CMS)

BTW, yes all full GCs in HotSpot are stop the world and so far only Parallel GC employs multiple threads for full collections

ayanamist 22:57

Param tuning is not a big problem in many company, but the best gc effect after tuning is.

Monica Beckwith 23:00

Ok. I understand. What is the live data set size for your 100g heap?

ayanamist 23:00

Yes we do not encounter fullgc on 64GB heap with forked but not community hbase 0.94 even on openjdk 6. But since larger heap brings out more problems, our hbase team is splitting hbase server to small unit using docker to decrease heap size.

@Monica Beckwith Also large than 64G. We have some 196G mem machines.

Reducing heap size and increasing unit count is not a ideal solution. It brings more work on operation and more mem overhead. So if jdk can improve its full gc performance, it will bring a lot wonderful things.

Monica Beckwith 23:04

Ok. We can work on this via email if you prefer… but if you could send more information on LDS and marking threshold and occupancy… it will give me a better idea of the workload pressure on G1

ayanamist 23:09

@Monica Beckwith Fine, i will forward this to our hbase team

Martijn Verburg 23:29

And please do grab a free trial copy of censum from – it will help you compare and contrast your GC behaviour before and after changes.