Support Java 11

[nwangtw]

Compiles ok with Java 11

[nwangtw]

#3266

[joshfischer1108]

You might need to update the JDK version in the travis file too. https://github.com/apache/incubator-heron/blob/master/.travis.yml

[nwangtw]

You might need to update the JDK version in the travis file too. https://github.com/apache/incubator-heron/blob/master/.travis.yml

The change should work for Java8 and above

[nwangtw]

Some unit test libraries are not Jdk11 compatible and need to be updated. :(

[joshfischer1108]

It might be better to move this branch from your forked repo into the main heron repo. This way people can help us complete this task by opening up PR's directly to this branch.

[nwangtw]

It might be better to move this branch from your forked repo into the main heron repo. This way people can help us complete this task by opening up PR's directly to this branch.

Ah, interesting. That is a great idea~

Pushed to java_11_support branch.
To https://github.com/twitter/heron.git

• [new branch] java_11_support -> java_11_support

[thinker0]

https://github.com/apache/incubator-heron/blob/master/heron/executor/src/python/heron_executor.py#L436-L449

https://github.com/apache/incubator-heron/blob/master/heron/executor/src/python/heron_executor.py#L476-L490

From 1.9 and above, it should change as follows.

-Xlog:gc=info:file=${APP}/logs/gc.log.$(/bin/date +%Y-%m-%d-%H%M%S):time,uptime,pid:filecount=5,filesize=4096

• https://medium.com/hotels-com-technology/what-to-do-about-the-garbage-collector-when-moving-from-java-8-to-java-11-71e60f9b81f
• https://dzone.com/articles/disruptive-changes-to-gc-logging-in-java-9

[thinker0]

#3399

[thinker0]

#3434

[nicknezis]

Can this Pull Request be closed due to the work done by @thinker0 in #3399 and #3434 ?