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https://issues.apache.org/jira/browse/HBASE-17039?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Charlie Qiangeng Xu updated HBASE-17039:
----------------------------------------
Description:
After increasing one of our clusters to 1600 nodes, we observed a large amount
of invalid region moves(more than 30k moves) fired by the balance chore. Thus
we simulated the problem and printed out the balance plan, only to find out
many servers that had two regions for a certain table(we use by table
strategy), sent out both regions to other two servers that have zero region.
In the SimpleLoadBalancer's balanceCluster function,
the code block that determines the underLoadedServers might have a problem:
if (load >= min && load > 0) {
continue; // look for other servers which haven't reached min
}
int regionsToPut = min - load;
if (regionsToPut == 0)
{
regionsToPut = 1;
}
if min is zero, some server that has load of zero, which equals to min would be
marked as underloaded, which would cause the phenomenon mentioned above.
Since we increased the cluster's size to 1600+, many tables that only have 1000
regions, now would encounter such issue.
By fixing it up, the balance plan went back to normal.
was:
After increasing one of our clusters to 1600 nodes, we observed a large amount
of invalid region moves(more than 30k moves) fired by the balance chore. Thus
we simulated the problem and printed out the balance plan, only to find out
many servers that had two regions for a certain table(we use by table
strategy), sent out both regions to other two servers that have zero region.
In the SimpleLoadBalancer's balanceCluster function,
the code block that determines the underLoadedServers might have a problem:
if (load >= min && load > 0) {
continue; // look for other servers which haven't reached min
}
int regionsToPut = min - load;
if (regionsToPut == 0)
{
regionsToPut = 1;
}
if min is zero, some server that has load of zero, which equals to min would be
marked as underloaded, which would cause the phenomenon mentioned above.
Since we increased the cluster's size to 1600+, many tables that only have 1000
regions, now would encounter such issue.
> SimpleLoadBalancer schedules large amount of invalid region moves
> -----------------------------------------------------------------
>
> Key: HBASE-17039
> URL: https://issues.apache.org/jira/browse/HBASE-17039
> Project: HBase
> Issue Type: Bug
> Components: Balancer
> Affects Versions: 2.0.0, 1.1.6, 1.2.3
> Reporter: Charlie Qiangeng Xu
> Assignee: Charlie Qiangeng Xu
> Fix For: 2.0.0, 1.1.6, 1.2.3
>
>
> After increasing one of our clusters to 1600 nodes, we observed a large
> amount of invalid region moves(more than 30k moves) fired by the balance
> chore. Thus we simulated the problem and printed out the balance plan, only
> to find out many servers that had two regions for a certain table(we use by
> table strategy), sent out both regions to other two servers that have zero
> region.
> In the SimpleLoadBalancer's balanceCluster function,
> the code block that determines the underLoadedServers might have a problem:
> if (load >= min && load > 0) {
> continue; // look for other servers which haven't reached min
> }
> int regionsToPut = min - load;
> if (regionsToPut == 0)
> {
> regionsToPut = 1;
> }
> if min is zero, some server that has load of zero, which equals to min would
> be marked as underloaded, which would cause the phenomenon mentioned above.
> Since we increased the cluster's size to 1600+, many tables that only have
> 1000 regions, now would encounter such issue.
> By fixing it up, the balance plan went back to normal.
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