Yang Jie created HADOOP-20066:
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Summary: LocalDirAllocator throws ArithmeticException instead of
DiskErrorException when every directory with free space fails the write check
Key: HADOOP-20066
URL: https://issues.apache.org/jira/browse/HADOOP-20066
Project: Hadoop Common
Issue Type: Bug
Components: fs
Reporter: Yang Jie
When the size is unknown, AllocatorPerContext#getLocalPathForWrite picks a
directory at random, weighted by its free space. If the chosen directory fails
createPath(), its space is subtracted from {{totalAvailable}} and it counts as
searched. A directory with no usable space still counts toward {{numDirs}}, so
after every directory with space has failed, {{totalAvailable}} is 0 while
{{numDirsSearched < numDirs}} still holds, and the next {{(r.nextLong() >>> 1)
% totalAvailable}} throws "ArithmeticException: / by zero".
This needs two or more directories, at least one with no usable space, and
every directory with space failing createPath(), for example a disk remounted
read-only. The allocator only rebuilds its context when the configuration
changes, so in a task or client JVM every such allocation fails from then on.
Callers expect a DiskErrorException, which is an IOException; they get an
unchecked exception instead, without the message that lists the directories.
The fix stops the loop once no space is left, so the existing
DiskErrorException is thrown. HADOOP-9079 reported this case in 2012 with the
same change, but it was never committed.
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