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https://issues.apache.org/jira/browse/FLINK-6020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15998814#comment-15998814
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ASF GitHub Bot commented on FLINK-6020:
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Github user netguy204 commented on the issue:

    https://github.com/apache/flink/pull/3525
  
    @StephanEwen Yes, I do have at least objects and classes being stored in a 
static context. Any easy example (that has also bitten me a few times) is the 
class cache that Avro maintains: 
    
    
https://github.com/apache/avro/blob/master/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificData.java#L146
    
    The Avro API's, unless told otherwise, will use a singleton instance of 
SpecificData and will access that shared cache.
    
    Would something like that be enough to cause the classloader to pass 
between jobs?


> Blob Server cannot handle multiple job submits (with same content) parallelly
> -----------------------------------------------------------------------------
>
>                 Key: FLINK-6020
>                 URL: https://issues.apache.org/jira/browse/FLINK-6020
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Distributed Coordination
>            Reporter: Tao Wang
>            Assignee: Tao Wang
>            Priority: Critical
>
> In yarn-cluster mode, if we submit one same job multiple times parallelly, 
> the task will encounter class load problem and lease occuputation.
> Because blob server stores user jars in name with generated sha1sum of those, 
> first writes a temp file and move it to finalialize. For recovery it also 
> will put them to HDFS with same file name.
> In same time, when multiple clients sumit same job with same jar, the local 
> jar files in blob server and those file on hdfs will be handled in multiple 
> threads(BlobServerConnection), and impact each other.
> It's better to have a way to handle this, now two ideas comes up to my head:
> 1. lock the write operation, or
> 2. use some unique identifier as file name instead of ( or added up to) 
> sha1sum of the file contents.



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