Java Replication error: NullPointerException SEVERE: SnapPull failed on
2009-09-22 nightly
------------------------------------------------------------------------------------------
Key: SOLR-1458
URL: https://issues.apache.org/jira/browse/SOLR-1458
Project: Solr
Issue Type: Bug
Components: replication (java)
Affects Versions: 1.4
Environment: CentOS x64
8GB RAM
Tomcat, running with 7G max memory; memory usage is <2GB, so it's not the
problem
Host a: master
Host b: slave
Multiple single core Solr instances, using JNDI.
Java replication
Reporter: Artem Russakovskii
After finally figuring out the new Java based replication, we have started both
the slave and the master and issued optimize to all master Solr instances. This
triggered some replication to go through just fine, but it looks like some of
it is failing.
Here's what I'm getting in the slave logs, repeatedly for each shard:
{code}
SEVERE: SnapPull failed
java.lang.NullPointerException
at
org.apache.solr.handler.SnapPuller.fetchLatestIndex(SnapPuller.java:271)
at
org.apache.solr.handler.ReplicationHandler.doFetch(ReplicationHandler.java:258)
at org.apache.solr.handler.SnapPuller$1.run(SnapPuller.java:159)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at
java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:181)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:205)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
{code}
If I issue an optimize again on the master to one of the shards, it then
triggers a replication and replicates OK. I have a feeling that these SnapPull
failures appear later on but right now I don't have enough to form a pattern.
Here's replication.properties on one of the failed slave instances.
{code}
cat data/replication.properties
#Replication details
#Wed Sep 23 19:35:30 PDT 2009
replicationFailedAtList=1253759730020,1253759700018,1253759670019,1253759640018,1253759610018,1253759580022,1253759550019,1253759520016,1253759490026,1253759460016
previousCycleTimeInSeconds=0
timesFailed=113
indexReplicatedAtList=1253759730020,1253759700018,1253759670019,1253759640018,1253759610018,1253759580022,1253759550019,1253759520016,1253759490026,1253759460016
indexReplicatedAt=1253759730020
replicationFailedAt=1253759730020
lastCycleBytesDownloaded=0
timesIndexReplicated=113
{code}
and another
{code}
cat data/replication.properties
#Replication details
#Wed Sep 23 18:42:01 PDT 2009
replicationFailedAtList=1253756490034,1253756460169
previousCycleTimeInSeconds=1
timesFailed=2
indexReplicatedAtList=1253756521284,1253756490034,1253756460169
indexReplicatedAt=1253756521284
replicationFailedAt=1253756490034
lastCycleBytesDownloaded=22932293
timesIndexReplicated=3
{code}
Some relevant configs:
In solrconfig.xml:
{code}
<!-- For docs see http://wiki.apache.org/solr/SolrReplication -->
<requestHandler name="/replication" class="solr.ReplicationHandler" >
<lst name="master">
<str name="enable">${enable.master:false}</str>
<str name="replicateAfter">optimize</str>
<str name="backupAfter">optimize</str>
<str name="commitReserveDuration">00:00:20</str>
</lst>
<lst name="slave">
<str name="enable">${enable.slave:false}</str>
<!-- url of master, from properties file -->
<str name="masterUrl">${master.url}</str>
<!-- how often to check master -->
<str name="pollInterval">00:00:30</str>
</lst>
</requestHandler>
{code}
The slave then has this in solrcore.properties:
{code}
enable.slave=true
master.url=URLOFMASTER/replication
{code}
and the master has
{code}
enable.master=true
{code}
I'd be glad to provide more details but I'm not sure what else I can do.
SOLR-926 may be relevant.
Thanks.
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