Japanese news show, Ali will release its 21 heavy OpenJDK release Alibaba Dragonwell.
We know that OpenJDK is based on JDK open source version of GPL v2 / Classpath Exception, many companies offer their release on the basis of OpenJDK on, such as Oracle, AdoptOpenJDK, Azul, IBM and Red Hat, in general these vendors will self-derived the OpenJDK version added some commercial / non-commercial support options.
Last year, AWS also launched its own OpenJDK release Corretto, behind even the father of Java James Gosling "Platform", a time caused no small repercussions.
The conventional understanding, AWS do Corretto can be considered a "create the wheel," but it provides long-term support, including security fixes, enhancements common, GC scheduling, to prevent memory overflow, as well as improved monitoring, reporting and thread management, the ability to coupled with strong customer and AWS Eco-dependent communities, there is reason to believe Corretto this wheel is a great practical significance.
Ali will be the release of Alibaba Dragonwell also claimed LTS, and customer and community development body mass Ali naturally Needless to say, then, Alibaba Dragonwell the OpenJDK releases will bring something to do with "making the wheel"?
Lee three red Ali cloud intelligent senior technical experts to open China to disclose some information about Alibaba Dragonwell in advance.
The first impression is Dragonwell name, Longjing tea? The moral is the same quality as Longjing it? Share ideas behind it.
Java itself is a coffee name, AWS is also an open source Corretto coffee names.
When choosing a name, we have to consider a lot. China's Java developers will be Alibaba Dragonwell important user groups, so we're looking for inspiration from some of the drink's name with Chinese characteristics, both on behalf of Chinese culture, but also hope to have the name of the very ambitious intentions, can her interpretation of the all-inclusive. The final thought of Hangzhou green tea - Longjing.
On the other hand, the English name Longjing Dragonwell also fits the meaning we want to express. One of the "well" of the word, it has a lot of water will come together, enjoy together the moral, just fit the spirit of open source collaboration to share ideas. This is the open-source JDK Ali's original intention, hope to bring together contributions of many developers, so that we can use for free with Java, Java promote progress together.
Why should we do this thing? Please tell us about the background.
We all know that Java has been dominated by Oracle, from the beginning of 2017, Oracle began to change after another several Java strategy. In 2018 CodeOne (formerly JavaOne) Conference, Chief Architect of the Java Platform Group from Mark Reinhold made "The Future of Java is Today" keynote speech, focusing on the changes in the release of Java mode.
He pointed out that, from Java 11 (included) and later versions start, Oracle will no longer provide free long-term support, if you need long-term support can be obtained through paid to Oracle way. The free update Java 8 will also be stopped in January 2019 (now stopped).
So unless you are the Oracle JDK or other commercial vendors paying customers, otherwise the only option is to maintain the community version of OpenJDK, Java developers can be expected to switch from Oracle JDK to OpenJDK open source phenomenon more and more.
Ali is arguably one of the world's largest user of Java, and the Java JDK is an infrastructure. We start from as early as 2010, it has developed and customized based on OpenJDK open source software. 9 years, underpinned Ali economies all Java business, after years of "double 11" test, accumulated a great deal of practical experience in the business scene.
As a general Ali so the amount of Java users, we have a responsibility, it is to open our JDK out to all Java users a new choice. Meanwhile, Ali's own terms, Alibaba Dragonwell will be two versions for Java 8 and Java 11 LTS Ali cloud VM image with the release of Ali cloud free to customers.
That Alibaba Dragonwell will be based on OpenJDK 8 and 11? Then the future will pay more attention to follow up the new features of Java or ensure the provision of support it? What is its future development vision or goal?
The release of a preview version of Alibaba Dragonwell 8 corresponds to the upstream version of OpenJDK 8. Alibaba Dragonwell as OpenJDK downstream, is a free JDK release, it will provide long-term support, including critical fixes and security updates.
Alibaba Dragonwell support x86-64 / Linux platform, which is characterized by, or pay attention to is: in the case of large-scale data center deployment of Java applications, stability, and improve efficiency and optimize performance.
Alibaba Dragonwell predecessor was AJDK Alibaba internal use, or another point of view, Alibaba Dragonwell is AJDK advantage successor. As the open source version of AJDK, Alibaba Dragonwell will follow AJDK technical advantages and practical scenarios accumulated technical experience.
AJDK there are numerous technical innovations, including multi-tenant, Wisp Association process technology and ZenGC, and we hope that gradually the internal Alibaba accumulation of technological innovation contribute to the OpenJDK open source community out, and settle down in Alibaba Dragonwell in.
When GA, there are currently no specific timetable for the various stages of release?
The current release version is Alibaba Dragonwell 8 Preview Preview, Alibaba Dragonwell will publish a quarterly update, the current plan is to release three months later Preview of GA. Alibaba Dragonwell 11 expected to be released by year end.
Alibaba Dragonwell 8 is a LTS version, its life cycle specifically what? Recently we related issue of open source license are afraid (that is, in fact, open source protocol may need to make changes according to the manufacturer), that the current / future Dragonwell will add some support restrictions it?
will not. Alibaba Dragonwell is OpenJDK downstream, we will strictly abide by the relevant principles and OpenJDK Community agreement.
Recently AWS also launched its own OpenJDK release Corretto; Even earlier, in fact, Azul and Red Hat and other vendors have provided OpenJDK version. So Ali Dragonwell What are the advantages and characteristics of it?
Also mentioned earlier, Alibaba Dragonwell pay attention to the data center in case of large-scale deployment of Java applications, stability, and improve efficiency and optimize performance.
Specifically:
To maintain close cooperation with the OpenJDK community, keep track of community work, timely synchronized upstream update.
Alibaba Dragonwell release is compatible with the Java SE standard.
Incubation of the AJDK innovative technology, will gradually contribute OpenJDK, and precipitation in Alibaba Dragonwell. For example, the release of version contains JWarmUp feature, which optimizes the JVM warm-up process after the restart, technical details can refer to the user manual.
Based on engineering practice Ali, Alibaba Dragonwell will choose an important function portable high versions of Java, these large-scale migration capabilities have been deployed inside Ali, users are free to use, without waiting for the next LTS version. For example, the version of Java 11 upstream migration of Java Flight Recorder (JFR) function, Java developers can through detailed profiling information collection process JFR JVM running, with the Java Mission Control (JMC), a substantial increase in the diagnosis of the problem Java applications efficiency and performance optimization. This is still stuck in the Java user 8, that was very meaningful.
Guest Introduction
Lee three red, Ali cloud intelligent senior technical experts. 2014 joined ants gold dress, Alibaba is now the person in charge of Java technology, has over 10 years of experience in Java development. Prior to joining Ali, a former IBM Java Technology Center, responsible person, involved in the development of the IBM Java Virtual Machine J9. Active in the Java technology community, has a number of patents in the field of the Java Virtual Machine, is an international conference organizers, JVM premier meeting JVMLS'17 invited speakers, JavaOne, QCon, JPoint and other GreenTea JUG (Java User Group) invited guests , VMIL'18 conference program committee.
I. Introduction:
March 21 Beijing will Yunfeng Ali, Alibaba announced the OpenJDK open source of foreign long-term support version of Alibaba Dragonwell. As the only representative of Chinese global management organization Java Java Community Process (JCP) executive committee of the highest, and OpenJDK Java ecosystem customized by one of the few outside of Oracle, Alibaba Dragonwell open source Alibaba weight to the global Java developers pound gift.
Alibaba has the most abundant Java application scenarios, covering many areas of electricity providers, finance and logistics, Java is one of the largest users in the world. As OpenJDK downstream, Alibaba Dragonwell Alibaba internal OpenJDK customized version AJDK open source version, AJDK online electricity providers, finance, logistics and optimized combination of business scenarios, Alibaba data centers running large scale 100000 + server . Alibaba Dragonwell compatible with the Java SE standard, currently only supports Linux / x86_64 platforms. Alibaba Dragonwell OpenJDK is downstream (friendly fork), and using the same OpenJDK licensing. Ali will be more closely with other open source OpenJDK community collaboration, contribute more patches, promote the sustainable development of Java technology.
Second, characteristics:
1, garbage collection: use CMS (-XX: + UseConcMarkSweep) as the default GC policy.
2、JFR（Java Flight Recorder）：
(1) from the JDK11 backport to Dragonwell-8 release.
(2) add a EnbleJFR command-line option, off by default, for complete isolation JFR associated logic, only add -XX: + EnableJFR to the JVM command line can use JFR characteristics.
3, Serviceability support:
(1) jmap the dump subcommand supports the "mini" option, you can ignore the contents of the original type of the array in doing heapdump, please refer to jmap tools help information.
(2) adding a parameter for printing a histogram young PrintYoungGenHistoAfterParNewGC object region after ParNew GC. This parameter can be opened jinfo dynamic.
(3) increase the parameter PrintGCRootsTraceTime for printing a specific time-consuming ParNew GC, mainly for troubleshooting ygc long. This parameter can be opened and closed by a dynamic jinfo.
(4) increasing the parameter ArrayAllocationWarningSize, the default value is 512M. When the size of the object exceeds the assigned value, the output on the standard display will stack allocation. This parameter can be changed dynamically by jinfo.
4, JWarmUp:
(1) increasing the parameter CompilationWarmUpRecording JWarmUp recording mode is enabled, and after a specified time, generates JVM JWarmUp profile, comprising the JVM loaded class and method hotspot.
(2) adding a parameter to enable JWarmUp CompilationWarmUp preheating compilation mode, according to the recording method of hot JWarmUp profile specified before loading the API may inform JVM preheated hot method compilation.
(3) JDK classes provided com.alibaba.jwarmup.JWarmUp, applications can use the JAVA API control JWarmUp, such as notifying the JVM WarmUp compiled, the compiler to check the situation, inform the compiled JVM preheat-off optimization.
Third, the installation Alibaba Dragonwell:
1, download packages:
Download: https: //github.com/alibaba/dragonwell8/releases
Download version: Alibaba_Dragonwell8_Linux_x64_8.0-preview.tar.gz
2, extract the package: # tar -xf Alibaba_Dragonwell8_Linux_x64_8.0-preview.tar.gz -C / usr / local
Note: The generated unpacked directory called j2sdk-image
3, configure the environment variables:
# vim /etc/profile.d/jdk.sh
export JAVA_HOME=/usr/local/j2sdk-image
export PATH=$JAVA_HOME/bin:$PATH
# . /etc/profile.d/jdk.sh
4. Check JAVA version: # java -version
