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https://issues.apache.org/jira/browse/CASSANDRA-9120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14494746#comment-14494746
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Ariel Weisberg commented on CASSANDRA-9120:
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I am on board with the patch for 2.0 and 2.1, but it seems like it could be a
little more accurate at calculating element size (I think it undercounts by a
large amount). If you instantiate a toy minimal size IndexInfo and invoke
memorySize() you should get a more accurate bound and can put that into a
static final field.
You can cache the result of maxMemory() in a static final field. Apparently it
is implemented as a JNI call (unless it is also an intrinsic which I wouldn't
expect).
The last thing to think about is estimateMemorySizeForKeys(int). It's a lot of
multiplication and division and some of the constants might not be fully
evaluated if they are tucked into a MemoryLayoutSpecification. I don't want to
get carried away trying to make it better, but I am uncomfortable because we
don't have a suite of benchmarks that will run to let us know if this change
has an impact. If you have a simple idea for how to make this approximation
simpler to calculate that would be great.
> OutOfMemoryError when read auto-saved cache (probably broken)
> -------------------------------------------------------------
>
> Key: CASSANDRA-9120
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9120
> Project: Cassandra
> Issue Type: Bug
> Environment: Linux
> Reporter: Vladimir
> Fix For: 3.0, 2.0.15, 2.1.5
>
>
> Found during tests on a 100 nodes cluster. After restart I found that one
> node constantly crashes with OutOfMemory Exception. I guess that auto-saved
> cache was corrupted and Cassandra can't recognize it. I see that similar
> issues was already fixed (when negative size of some structure was read).
> Does auto-saved cache have checksum? it'd help to reject corrupted cache at
> the very beginning.
> As far as I can see current code still have that problem. Stack trace is:
> {code}
> INFO [main] 2015-03-28 01:04:13,503 AutoSavingCache.java (line 114) reading
> saved cache
> /storage/core/loginsight/cidata/cassandra/saved_caches/system-sstable_activity-KeyCache-b.db
> ERROR [main] 2015-03-28 01:04:14,718 CassandraDaemon.java (line 513)
> Exception encountered during startup
> java.lang.OutOfMemoryError: Java heap space
> at java.util.ArrayList.<init>(Unknown Source)
> at
> org.apache.cassandra.db.RowIndexEntry$Serializer.deserialize(RowIndexEntry.java:120)
> at
> org.apache.cassandra.service.CacheService$KeyCacheSerializer.deserialize(CacheService.java:365)
> at
> org.apache.cassandra.cache.AutoSavingCache.loadSaved(AutoSavingCache.java:119)
> at
> org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:262)
> at
> org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:421)
> at
> org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:392)
> at org.apache.cassandra.db.Keyspace.initCf(Keyspace.java:315)
> at org.apache.cassandra.db.Keyspace.<init>(Keyspace.java:272)
> at org.apache.cassandra.db.Keyspace.open(Keyspace.java:114)
> at org.apache.cassandra.db.Keyspace.open(Keyspace.java:92)
> at
> org.apache.cassandra.db.SystemKeyspace.checkHealth(SystemKeyspace.java:536)
> at
> org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:261)
> at
> org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:496)
> at
> org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:585)
> {code}
> I looked at source code of Cassandra and see:
> http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/2.0.10/org/apache/cassandra/db/RowIndexEntry.java
> 119 int entries = in.readInt();
> 120 List<IndexHelper.IndexInfo> columnsIndex = new
> ArrayList<IndexHelper.IndexInfo>(entries);
> It seems that value entries is invalid (negative) and it tries too allocate
> an array with huge initial capacity and hits OOM. I have deleted saved_cache
> directory and was able to start node correctly. We should expect that it may
> happen in real world. Cassandra should be able to skip incorrect cached data
> and run.
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