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https://issues.apache.org/jira/browse/ACCUMULO-2694?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Busbey updated ACCUMULO-2694:
----------------------------------
Component/s: (was: tserver)
Description:
Both DefaultLoadBalancer and ChaoticLoadBalancer won't balance if there are
outstanding migrations.
In this instance, we have offline tables from previous CI runs. one of these
tables had outstanding migrations
{noformat}
2014-04-17 09:47:34,716 [balancer.TabletBalancer] DEBUG: Scanning tablet server
a2438.halxg.cloudera.com:10011[544d5edf1fec529] for table 8
2014-04-17 09:47:36,217 [balancer.TabletBalancer] DEBUG: Scanning tablet server
a2416.halxg.cloudera.com:10011[244d5edf0b0c4ff] for table 8
2014-04-17 09:47:36,222 [balancer.DefaultLoadBalancer] DEBUG: balance ended
with 4 migrations
2014-04-17 09:47:36,222 [balancer.DefaultLoadBalancer] DEBUG: balance ended
with 0 migrations
2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;4aa09c;4a809d:
a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;7e603;7e4029:
a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;21a044;21803d:
a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
2014-04-17 09:47:36,223 [master.Master] DEBUG: migration 8;59c02e;59a02b:
a2416.halxg.cloudera.com:10011[244d5edf0b0c4ff] ->
a2414.halxg.cloudera.com:10011[444d5f6b43ac4aa]
{noformat}
Later messages show these tablets being unloaded successfully. However, since
the table is offline they never get loaded on the new tablet server. This means
they never leave the queue, so balancing stops.
As an added complication, this last set of migrations was added after the table
was already offline. I think this is because there had been unhosted tablets
which caused a bunch of contention around when balancing would finally happen.
A few needed changes:
# If the balancer isn't going to balance it needs a log message saying so.
Ideally, this message should also include information about the outstanding
migrations that are blocking it.
# the Migration cleanup thread should look for migrations involving offline
tables and clear them (I'd prefer this to trying to have the balancer figure
out if a table is offline or online)
# When we offline a table, we should probably clear migrations related to that
table. This isn't strictly necessary if the cleanup thread will get them
eventually, but it would speed things up.
Workarounds:
# migration state is only stored in Master memory, failing over to a different
master will force recalculation which will not include offline tables.
# if for some reason you can't handle a failure of the current master, bringing
the involved table back online (which might mean all offline tables) will allow
migrations to resume. the table must remain online until there are no longer
migrations involving it.
# I *think* that if you clone the offline table and then delete the original,
that will clear the outstanding migrations related to it. I did not test this,
because the above two options are much better.
The latter option will cause considerably more churn, especially if the offline
table isn't actually providing utility.
was:
Started CI with a 10-tablet pre-split table. For some reason this table is not
balancing to the other tablet servers.
Will look at logs in the morning.
Environment: 1.6.0-RC2 Started CI with a 10-tablet pre-split table.
(was: 1.6.0-RC2)
Affects Version/s: 1.4.0
1.5.0
Summary: Offline tables block balancing for online tables (was:
Table not balancing during Continuous Ingest)
> Offline tables block balancing for online tables
> ------------------------------------------------
>
> Key: ACCUMULO-2694
> URL: https://issues.apache.org/jira/browse/ACCUMULO-2694
> Project: Accumulo
> Issue Type: Bug
> Components: master
> Affects Versions: 1.4.0, 1.5.0, 1.6.0
> Environment: 1.6.0-RC2 Started CI with a 10-tablet pre-split table.
> Reporter: Mike Drob
> Priority: Critical
> Fix For: 1.4.6, 1.5.2, 1.6.1, 1.7.0
>
>
> Both DefaultLoadBalancer and ChaoticLoadBalancer won't balance if there are
> outstanding migrations.
> In this instance, we have offline tables from previous CI runs. one of these
> tables had outstanding migrations
> {noformat}
> 2014-04-17 09:47:34,716 [balancer.TabletBalancer] DEBUG: Scanning tablet
> server a2438.halxg.cloudera.com:10011[544d5edf1fec529] for table 8
> 2014-04-17 09:47:36,217 [balancer.TabletBalancer] DEBUG: Scanning tablet
> server a2416.halxg.cloudera.com:10011[244d5edf0b0c4ff] for table 8
> 2014-04-17 09:47:36,222 [balancer.DefaultLoadBalancer] DEBUG: balance ended
> with 4 migrations
> 2014-04-17 09:47:36,222 [balancer.DefaultLoadBalancer] DEBUG: balance ended
> with 0 migrations
> 2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;4aa09c;4a809d:
> a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
> a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
> 2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;7e603;7e4029:
> a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
> a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
> 2014-04-17 09:47:36,222 [master.Master] DEBUG: migration 8;21a044;21803d:
> a2438.halxg.cloudera.com:10011[544d5edf1fec529] ->
> a2422.halxg.cloudera.com:10011[3451dd2d9fa6761]
> 2014-04-17 09:47:36,223 [master.Master] DEBUG: migration 8;59c02e;59a02b:
> a2416.halxg.cloudera.com:10011[244d5edf0b0c4ff] ->
> a2414.halxg.cloudera.com:10011[444d5f6b43ac4aa]
> {noformat}
> Later messages show these tablets being unloaded successfully. However, since
> the table is offline they never get loaded on the new tablet server. This
> means they never leave the queue, so balancing stops.
> As an added complication, this last set of migrations was added after the
> table was already offline. I think this is because there had been unhosted
> tablets which caused a bunch of contention around when balancing would
> finally happen.
> A few needed changes:
> # If the balancer isn't going to balance it needs a log message saying so.
> Ideally, this message should also include information about the outstanding
> migrations that are blocking it.
> # the Migration cleanup thread should look for migrations involving offline
> tables and clear them (I'd prefer this to trying to have the balancer figure
> out if a table is offline or online)
> # When we offline a table, we should probably clear migrations related to
> that table. This isn't strictly necessary if the cleanup thread will get them
> eventually, but it would speed things up.
> Workarounds:
> # migration state is only stored in Master memory, failing over to a
> different master will force recalculation which will not include offline
> tables.
> # if for some reason you can't handle a failure of the current master,
> bringing the involved table back online (which might mean all offline tables)
> will allow migrations to resume. the table must remain online until there are
> no longer migrations involving it.
> # I *think* that if you clone the offline table and then delete the original,
> that will clear the outstanding migrations related to it. I did not test
> this, because the above two options are much better.
> The latter option will cause considerably more churn, especially if the
> offline table isn't actually providing utility.
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