bringhurst opened a new pull request, #1716:
URL: https://github.com/apache/samza/pull/1716

   Several possible issues were identified in run-class.sh, including:
   
   ## Race condition in pathing jar manifest creation
   
   A race condition exists when setting up the classpath during container 
launch.
   
   During container launch using samza-yarn, run-class.sh creates a pathing jar 
file (which holds the classpath for the container launch). However, during the 
creation of this pathing jar, temporary files, as well as the pathing jar 
itself is not placed in a location unique to the container. This results in 
multiple containers writing to the same pathing jar location and temporary file 
location, which results in a race condition.
   
   This race condition may show up in several ways, such as when Yarn removes 
jars from a finished container (other containers will point to a classpath 
which no longer exists) or when multiple run-class.sh scripts attempt to write 
the manifest.txt or pathing jar at the same time.
   
   Note that host affinity being enabled will make this problem worse. The 
pathing.jar is written to the usercache, so when the container which created 
the pathing.jar is finished and removed, any new container which launches on 
that host will point to jar files which do not exist anymore. When host 
affinity is enabled, it will not move to a new host and just keep failing.
   
   ## Container logging directory fallback is not unique for each container
   
   The fallback log directory is the same among all containers running on the 
same host. It should be unique per-container.
   
   ## Container tmp dir is not unique per-container
   
   The JAVA_TMP_DIR directory is the same for all containers. We should make 
sure that it's safe to use the same directory for all containers.
   
   BUG=SAMZA-2804


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