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https://issues.apache.org/jira/browse/KUDU-2188?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16199565#comment-16199565
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Dan Burkert commented on KUDU-2188:
-----------------------------------
Fixed by
https://github.com/apache/kudu/commit/afdeb9ea218216631ae325b3205c23adb1061037
This issue caused the kudu-client 1.0.0, 1.1.0, 1.2.0, 1.3.0, 1.4.0, and 1.5.0
published jars to be non-compatible with JRE 8. Since it's not a regression
and no one has ever filed a bug about it, I don't think we should consider this
an issue worthy of special patch release.
> kudu-client JAR built via JDK8 depends on Java 8 APIs
> -----------------------------------------------------
>
> Key: KUDU-2188
> URL: https://issues.apache.org/jira/browse/KUDU-2188
> Project: Kudu
> Issue Type: Bug
> Components: java
> Affects Versions: 1.5.0
> Reporter: Adar Dembo
> Assignee: Adar Dembo
> Priority: Critical
>
> Even though we build our Java artifacts against JDK7 (by specifying
> source=1.7 and target=1.7) and we try to avoid introducing Java 8 only
> dependencies, there is one case where we've failed to do that. The issue is
> with ConcurrentHashMap.keySet(), which returns a Set in Java 7 and a
> ConcurrentHashMap.KeySetView in Java 8. The latter is a class that only
> exists in Java 8, but because it's a subtype of Set, it's legal to make that
> kind of API change.
> We use ConcurrentHashMap.keySet() in our Statistics.getTableSet() method, and
> as a result, if you build kudu-client using JDK8, you'll end up with a
> reference to a class that's only found in Java 8.
> I wrote a small test program to verify that this is indeed a problem:
> {noformat}
> import org.apache.kudu.client.Statistics;
> class Main {
> public static void main(String[] args) {
> Statistics s = new Statistics();
> s.getTabletSet();
> }
> }
> {noformat}
> And, after first building the kudu-client JAR with JDK8, here is how I
> compiled and ran the test program:
> {noformat}
> $ /opt/toolchain/openjdk-64bit-1.7.0.6/bin/javac -cp
> kudu/java/kudu-client/target/kudu-client-1.6.0-SNAPSHOT.jar Main.java
> $ /opt/toolchain/openjdk-64bit-1.7.0.6/bin/java -cp
> kudu/java/kudu-client/target/kudu-client-1.6.0-SNAPSHOT.jar:. Main
> Exception in thread "main" java.lang.NoSuchMethodError:
> java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
> at org.apache.kudu.client.Statistics.getTabletSet(Statistics.java:144)
> at Main.main(Main.java:6)
> {noformat}
> I don't know which of our release artifacts have this issue. This Statistics
> API is quite old so it presumably affects any that have been built by RMs
> using JDK8 rather than JDK7.
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