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From "Mathieu Roy (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-10501) Failure to start up Cassandra when temporary compaction files are not all renamed after kill/crash (FSReadError)
Date Fri, 09 Oct 2015 21:29:06 GMT
Mathieu Roy created CASSANDRA-10501:
---------------------------------------

             Summary: Failure to start up Cassandra when temporary compaction files are not
all renamed after kill/crash (FSReadError)
                 Key: CASSANDRA-10501
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10501
             Project: Cassandra
          Issue Type: Bug
          Components: Core
         Environment: Cassandra 2.1.6
Redhat Linux
            Reporter: Mathieu Roy


We have seen an issue intermittently but repeatedly over the last few months where, after
exiting the Cassandra process, it fails to start with an FSReadError (stack trace below).
The FSReadError refers to a 'statistics' file for a  that doesn't exist, though a corresponding
temporary file does exist (eg. there is no /media/data/cassandraDB/data/clusteradmin/singleton_token-01a92ed069b511e59b2c53679a538c14/clusteradmin-singleton_token-ka-9-Statistics.db
file, but there is a /media/data/cassandraDB/data/clusteradmin/singleton_token-01a92ed069b511e59b2c53679a538c14/clusteradmin-singleton_token-tmp-ka-9-Statistics.db
file.)

We tracked down the issue to the fact that the process exited with leftover compactions and
some of the 'tmp' files for the SSTable had been renamed to final files, but not all of them
- the issue happens if the 'Statistics' file is not renamed but others are. The scenario we've
seen on the last two occurrences involves the 'CompressionInfo' file being a final file while
all other files for the SSTable generation were left with 'tmp' names.

When this occurs, Cassandra cannot start until the file issue is resolved; we've worked around
it by deleting the SSTable files from the same generation, both final and tmp, which at least
allows Cassandra to start. Renaming all files to either tmp or final names would also work.

We've done some debugging in Cassandra and have been unable to cause the issue without renaming
the files manually. The rename code at SSTableWriter.rename() looks like it could result in
this if the process exits in the middle of the rename, but in every occurrence we've debugged
through, the Set of components is ordered and Statistics is the first file renamed.

However the comments in SSTableWriter.rename() suggest that the 'Data' file is meant to be
used as meaning the files were completely renamed. The method ColumnFamilyStore. removeUnfinishedCompactionLeftovers(),
however, will proceed assuming the compaction is complete if any of the component files has
a final name, and will skip temporary files when reading the list. If the 'Statistics' file
is temporary then it won't be read, and the defaults does not include a list of ancestors,
leading to the NullPointerException.

It appears that ColumnFamilyStore. removeUnfinishedCompactionLeftovers() should perhaps either
ensure that all 'tmp' files are properly renamed before it uses them, or skip SSTable files
that don't have either the 'Data' or 'Statistics' file in final form.

Stack trace: 
FSReadError in Failed to remove unfinished compaction leftovers (file: /media/data/cassandraDB/data/clusteradmin/singleton_token-01a92ed069b511e59b2c53679a538c14/clusteradmin-singleton_token-ka-9-Statistics.db).
 See log for details.
        at org.apache.cassandra.db.ColumnFamilyStore.removeUnfinishedCompactionLeftovers(ColumnFamilyStore.java:617)
        at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:302)
        at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:536)
        at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:625)
Caused by: java.lang.NullPointerException
        at org.apache.cassandra.db.ColumnFamilyStore.removeUnfinishedCompactionLeftovers(ColumnFamilyStore.java:609)
        ... 3 more
Exception encountered during startup: java.lang.NullPointerException




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