Sahil Takiar created IMPALA-8568:
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Summary: Fix Impala JNI warnings when -Xcheck:jni is enabled
Key: IMPALA-8568
URL: https://issues.apache.org/jira/browse/IMPALA-8568
Project: IMPALA
Issue Type: Improvement
Reporter: Sahil Takiar
Assignee: Sahil Takiar
IMPALA-8250 made a lot of improvements to our usage of the JNI. Impala no
longer crashes when running exhaustive tests with -Xcheck:jni enabled. We made
some progress in cleaning up libhdfs JNI usage in HDFS-14321 and HDFS-14348 as
well.
However, re-running exhaustive tests with -Xcheck:jni still shows a lot of
warnings. It's not clear if these warnings are from libhdfs or Impala, but
either way we should drive a fix.
The most concerning of the current list of JNI warnings produced by Impala, are
the "JNI call made without checking exceptions when required to from ..."
warnings. Essentially, this means that when making a JNI call, we are not
properly checking for exceptions. This can be problematic because a JNI call
make throw an exception, and we end up swallowing it.
There are lots of warnings about "WARNING: JNI local refs: [x], exceeds
capacity: [y]". Based on some digging (e.g.
https://community.oracle.com/message/13290783) it looks like these warnings
aren't fatal, but are just bad practice. I think we can fix the most egregious
offenders (looks like the HBase code is one of them), and hopefully live with
the rest (a lot of the warnings are thrown by internal Java code as well).
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