Aaron Morton created CASSANDRA-4223:
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Summary: Non Unique Streaming session ID's
Key: CASSANDRA-4223
URL: https://issues.apache.org/jira/browse/CASSANDRA-4223
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.0.9
Environment: Ubuntu 10.04.2 LTS
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02, mixed mode)
"Bare metal" servers from https://www.stormondemand.com/servers/baremetal.html
The servers run on a custom hypervisor.
Reporter: Aaron Morton
Assignee: Aaron Morton
I have observed repair processes failing due to duplicate Streaming session
ID's. In this installation it is preventing rebalance from completing. I
believe it has also prevented repair from completing in the past.
The attached streaming-logs.txt file contains log messages and an explanation
of what was happening during a repair operation. it has the evidence for
duplicate session ID's.
The duplicate session id's were generated on the repairing node and sent to the
streaming node. The streaming source replaced the first session with the second
which resulted in both sessions failing when the first FILE_COMPLETE message
was received.
The errors were:
{code:java}
DEBUG [MiscStage:1] 2012-05-03 21:40:33,997 StreamReplyVerbHandler.java (line
47) Received StreamReply StreamReply(sessionId=26132848816442266,
file='/var/lib/cassandra/data/FMM_Studio/PartsData-hc-1-Data.db',
action=FILE_FINISHED)
ERROR [MiscStage:1] 2012-05-03 21:40:34,027 AbstractCassandraDaemon.java (line
139) Fatal exception in thread Thread[MiscStage:1,5,main]
java.lang.IllegalStateException: target reports current file is
/var/lib/cassandra/data/FMM_Studio/PartsData-hc-1-Data.db but is null
at
org.apache.cassandra.streaming.StreamOutSession.validateCurrentFile(StreamOutSession.java:195)
at
org.apache.cassandra.streaming.StreamReplyVerbHandler.doVerb(StreamReplyVerbHandler.java:58)
at
org.apache.cassandra.net.MessageDeliveryTask.run(MessageDeliveryTask.java:59)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown
Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
{code}
and
{code:java}
DEBUG [MiscStage:2] 2012-05-03 21:40:36,497 StreamReplyVerbHandler.java (line
47) Received StreamReply StreamReply(sessionId=26132848816442266,
file='/var/lib/cassandra/data/OpsCenter/rollups7200-hc-3-Data.db',
action=FILE_FINISHED)
ERROR [MiscStage:2] 2012-05-03 21:40:36,497 AbstractCassandraDaemon.java (line
139) Fatal exception in thread Thread[MiscStage:2,5,main]
java.lang.IllegalStateException: target reports current file is
/var/lib/cassandra/data/OpsCenter/rollups7200-hc-3-Data.db but is null
at
org.apache.cassandra.streaming.StreamOutSession.validateCurrentFile(StreamOutSession.java:195)
at
org.apache.cassandra.streaming.StreamReplyVerbHandler.doVerb(StreamReplyVerbHandler.java:58)
at
org.apache.cassandra.net.MessageDeliveryTask.run(MessageDeliveryTask.java:59)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown
Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
{code}
I think this is because System.nanoTime() is used for the session ID when
creating the StreamInSession objects (driven from
StorageService.requestRanges()) .
>From the documentation
>(http://docs.oracle.com/javase/6/docs/api/java/lang/System.html#nanoTime())
{quote}
This method provides nanosecond precision, but not necessarily nanosecond
accuracy. No guarantees are made about how frequently values change.
{quote}
Also some info here on clocks and timers
https://blogs.oracle.com/dholmes/entry/inside_the_hotspot_vm_clocks
The hypervisor may be at fault here. But it seems like we cannot rely on
successive calls to nanoTime() to return different values.
To avoid message/interface changes on the StreamHeader it would be good to keep
the session ID a long. The simplest approach may be to make successive calls to
nanoTime until the result changes. We could fail if a certain number of
milliseconds have passed.
Hashing the file names and ranges is also a possibility, but more involved.
(We may also want to drop latency times that are 0 nano seconds.)
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