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https://issues.apache.org/jira/browse/HADOOP-8756?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Colin Patrick McCabe updated HADOOP-8756:
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Description:
We use {{System.loadLibrary("snappy")}} from the Java side. However in
libhadoop, we use {{dlopen}} to open libsnappy.so dynamically.
System.loadLibrary uses {{java.library.path}} to resolve libraries, and
{{dlopen}} uses {{LD_LIBRARY_PATH}} and the system paths to resolve libraries.
Because of this, the two library loading functions can be at odds.
We should fix this so we only load the library once, preferably using the
standard Java {{java.library.path}}.
We should also log the search path(s) we use for {{libsnappy.so}} when loading
fails, so that it's easier to diagnose configuration issues.
was:
* We use {{System.loadLibrary("snappy")}} from the Java side. However in
libhadoop, we use {{dlopen}} to open libsnappy.so dynamically. It seems like
the System.loadLibrary nonsense is completely redundant-- we would only need
this if we planned on accessing libsnappy methods directly from Java (via the
'native' keyword)- - which we don't, and can't, since snappy is not JNI. At
the end of the day, snappy is only accessible through libhadoop.so, so I think
snappy-related issues should be handled there.
* We should log the search path(s) we use for {{libsnappy.so}}, so that it's
easier to diagnose configuration issues.
> libsnappy loader issues
> -----------------------
>
> Key: HADOOP-8756
> URL: https://issues.apache.org/jira/browse/HADOOP-8756
> Project: Hadoop Common
> Issue Type: Bug
> Components: native
> Affects Versions: 2.2.0-alpha
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Priority: Minor
>
> We use {{System.loadLibrary("snappy")}} from the Java side. However in
> libhadoop, we use {{dlopen}} to open libsnappy.so dynamically.
> System.loadLibrary uses {{java.library.path}} to resolve libraries, and
> {{dlopen}} uses {{LD_LIBRARY_PATH}} and the system paths to resolve
> libraries. Because of this, the two library loading functions can be at odds.
> We should fix this so we only load the library once, preferably using the
> standard Java {{java.library.path}}.
> We should also log the search path(s) we use for {{libsnappy.so}} when
> loading fails, so that it's easier to diagnose configuration issues.
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