Hi commiters and users of Hadoop stack, I’ll share the current status of JDK-8 support here. We can take a two-step approach to support JDK-8 - runtime-level support and source-level support.
About runtime-level support, I’ve tested Hadoop stack with JDK-8 e.g. MapReduce, Spark, Tez, Flink on YARN and HDFS for a few months. As long as I tested, it works well completely since JDK-8 doesn’t have any incompatibility at binary level. We can say Hadoop has supported JDK8 runtime already. Do you have any concern about this? I’ve not tested with HBase yet. I need help of HBase community. I think only problem about runtime is HADOOP-11364, default value of colntainer-killer of YARN. After fixing the issue, we can declare the support of JDK on Hadoop Wiki to make it clear for users. https://wiki.apache.org/hadoop/HadoopJavaVersions About source-level, however, we have one big problem - upgrading dependency of asm and cglib. We need to upgrade all libraries which depends on asm to support new byte code introduced in JDK8[1]. The dependencies which uses asm are jersey-server for compile and provide scope, and cglib for test scope(I checked it with mvn dependency:tree command). HADOOP-9613 is addressing the problem. One complex problem I’ve faced is Jersey depends on grizzly - to upgrade jersey to 1.19, which supports JDK8, we need to upgrade grizzly to 2.2.16 to use jersey-test-framework-grizzly2. I’d like to discuss which version we will target this change. Can we do this in branch-2? Should we take care of HADOOP-11656 and HADOOP-11993 at the same time? I’d also confirm whether HADOOP-11993 means to remove Jersey, which depends on asm, or not. I think we can collaborate with Yetus community here. Also, another simple problem is that source code cannot be compiled because javadoc format or variable identifier are illegal(e.g. HADOOP-12457, HADOOP-11875). I think this can be solved straightforwardly. Please share any concern I’ve missed. The opinions of users are also welcome :-) I'd like to go forward this step by step to make Hadoop user friendly. Thanks Steve, Sean, Allen, Robert, Brahma, Akira, Larry, Allen, Andrew Purtell, Tsz-wo Sze, Sethen and other guys for having lots works about JDK-8. Best regards, - Tsuyoshi [1] http://product.hubspot.com/blog/upgrading-to-java-8-at-scale [2] http://ispras.linuxbase.org/index.php/Java_API_Compliance_Checker
