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https://issues.apache.org/jira/browse/HADOOP-11211?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14219825#comment-14219825
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Gera Shegalov commented on HADOOP-11211:
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[~timyitong], sorry for confusion, I did not realize it was your intention to
add wording about the nested classes. The reason for confusion is that patterns
with '$' are not supported and it was the patch MAPREDUCE-6128.v05.patch that
tried to add this pattern.
HADOOP-11309 implements matching all nested classes of the class C if the
pattern is a single class C.
If you want to be precise, you can spell out the format of system.classes:
comma-separated list of patterns.
A pattern may define an inclusion (positive):
# A single class 'C' that matches C and transitively all nested classes C$*
defined in C
# A package name followed by a '.' (e.g., "com.example.") that matches all
classes files from the package
Exclusion can be defined by a negative pattern -P if P is a positive pattern as
defined above.
A class is considered a system class if and only if it matches one of the
positive patterns and none of the negative ones. More formally:
A class is member of the Inclusion set {{I}} if it is matched by one of the
positive patterns. A class is member of the Exclusion set {{E}} if it is
matched by one of negative patterns P. The set of system classes {{S = I \ E}}
> mapreduce.job.classloader.system.classes property behaves differently when
> the exclusion and inclusion order is different
> -------------------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-11211
> URL: https://issues.apache.org/jira/browse/HADOOP-11211
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: hudson
> Reporter: Yitong Zhou
> Assignee: Yitong Zhou
> Fix For: hudson
>
> Attachments: HADOOP-11211.patch
>
>
> If we want to include package foo.bar.* but exclude all sub packages named
> foo.bar.tar.* in system classes, configuring
> "mapreduce.job.classloader.system.classes=foo.bar.,-foo.bar.tar." won't work.
> foo.bar.tar will still be pulled in. But if we change the order:
> "mapreduce.job.classloader.system.classes=-foo.bar.tar.,foo.bar.", then it
> will work.
> This bug is due to the implementation of ApplicationClassLoaser#isSystemClass
> in hadoop-common, where we simply return the matching result immediately when
> the class name hits the first match (either positive or negative).
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