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https://issues.apache.org/jira/browse/HADOOP-15859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16654074#comment-16654074
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Kihwal Lee commented on HADOOP-15859:
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+1 We've applied the same patch internally.
> ZStandardDecompressor.c mistakes a class for an instance
> --------------------------------------------------------
>
> Key: HADOOP-15859
> URL: https://issues.apache.org/jira/browse/HADOOP-15859
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.9.0, 3.0.0-alpha2
> Reporter: Ben Lau
> Assignee: Jason Lowe
> Priority: Blocker
> Attachments: HADOOP-15859.001.patch
>
>
> As a follow up to HADOOP-15820, I was doing more testing on ZSTD compression
> and still encountered segfaults in the JVM in HBase after that fix.
> I took a deeper look and realized there is still another bug, which looks
> like it's that we are actually [calling
> setInt()|https://github.com/apache/hadoop/blob/f13e231025333ebf80b30bbdce1296cef554943b/hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/compress/zstd/ZStandardDecompressor.c#L148]
> on the "remaining" variable on the ZStandardDecompressor class itself
> (instead of an instance of that class) because the Java stub for the native C
> init() function [is marked
> static|https://github.com/apache/hadoop/blob/a0a276162147e843a5a4e028abdca5b66f5118da/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zstd/ZStandardDecompressor.java#L253],
> leading to memory corruption and a crash during GC later.
> Initially I thought we would fix this by changing the Java init() method to
> be non-static, but it looks like the "remaining" setInt() call is actually
> unnecessary anyway, because in ZStandardDecompressor.java's reset() we [set
> "remaining" to 0 right after calling the JNI init()
> call|https://github.com/apache/hadoop/blob/a0a276162147e843a5a4e028abdca5b66f5118da/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zstd/ZStandardDecompressor.java#L216].
> So ZStandardDecompressor.java init() doesn't have to be changed to an
> instance method, we can leave it as static, but remove the JNI init() call's
> "remaining" setInt() call altogether.
> Furthermore we should probably clean up the class/instance distinction in the
> C file because that's what led to this confusion. There are some other
> methods where the distinction is incorrect or ambiguous, we should fix them
> to prevent this from happening again.
> I talked to [~jlowe] who further pointed out the ZStandardCompressor also has
> similar problems and needs to be fixed too.
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