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From "James Taylor (JIRA)" <>
Subject [jira] [Commented] (PHOENIX-4010) Hash Join cache may not be send to all regionservers when we have stale HBase meta cache
Date Fri, 14 Jul 2017 01:02:00 GMT


James Taylor commented on PHOENIX-4010:

Thanks for the patch, []. Looks good, but instead of a static Cache in HashCacheClient,
how about storing it elsewhere, perhaps on TableResultIterator so you don't even need a Cache?
+    public static Cache<Long, HashJoinCache> joinCache ;
As far as the memory usage on the client, we track this with this code in ServerCacheClient:
    public ServerCache addServerCache(ScanRanges keyRanges, final ImmutableBytesWritable cachePtr,
final byte[] txState, final ServerCacheFactory cacheFactory, final TableRef cacheUsingTableRef)
throws SQLException {
        ConnectionQueryServices services = connection.getQueryServices();
        MemoryChunk chunk = services.getMemoryManager().allocate(cachePtr.getLength());
        List<Closeable> closeables = new ArrayList<Closeable>();
The chunk is added to the closables and then freed in the finally block. By holding on to
it now, we shouldn't free it until the removeServerCache call. You can do this in the ServerCache.close()
method after the call to removeServerCache here (just pass the chunk through the ServerCache
        public void close() throws SQLException {
            removeServerCache(id, servers);
The idea with the MemoryManager off of QueryServices is to track memory usage at a course
grain, potentially throttling or refusing allocation if too much is used.

> Hash Join cache may not be send to all regionservers when we have stale HBase meta cache
> ----------------------------------------------------------------------------------------
>                 Key: PHOENIX-4010
>                 URL:
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Ankit Singhal
>            Assignee: Ankit Singhal
>             Fix For: 4.12.0
>         Attachments: PHOENIX-4010.patch, PHOENIX-4010_v1.patch
>  If the region locations changed and our HBase meta cache is not updated then we might
not be sending hash join cache to all region servers hosting the regions.
> ConnectionQueryServicesImpl#getAllTableRegions
> {code}
> boolean reload =false;
>         while (true) {
>             try {
>                 // We could surface the package projected HConnectionImplementation.getNumberOfCachedRegionLocations
>                 // to get the sizing info we need, but this would require a new class
in the same package and a cast
>                 // to this implementation class, so it's probably not worth it.
>                 List<HRegionLocation> locations = Lists.newArrayList();
>                 byte[] currentKey = HConstants.EMPTY_START_ROW;
>                 do {
>                     HRegionLocation regionLocation = connection.getRegionLocation(
>                             TableName.valueOf(tableName), currentKey, reload);
>                     locations.add(regionLocation);
>                     currentKey = regionLocation.getRegionInfo().getEndKey();
>                 } while (!Bytes.equals(currentKey, HConstants.EMPTY_END_ROW));
>                 return locations;
> {code}
> Skipping duplicate servers in ServerCacheClient#addServerCache
> {code}
> List<HRegionLocation> locations = services.getAllTableRegions(cacheUsingTable.getPhysicalName().getBytes());
>             int nRegions = locations.size();
> .....
>  if ( ! servers.contains(entry) && 
>                         keyRanges.intersectRegion(regionStartKey, regionEndKey,
>                                 cacheUsingTable.getIndexType() == IndexType.LOCAL)) {
>                     // Call RPC once per server
>                     servers.add(entry);
> {code}
> For eg:- Table ’T’ has two regions R1 and R2 originally hosted on regionserver RS1.

> while Phoenix/Hbase connection is still active, R2 is transitioned to RS2 ,  but stale
meta cache will still give old region locations i.e R1 and R2 on RS1 and when we start copying
hash table, we copy for R1 and skip R2 as they are hosted on same regionserver. so, the query
on a table will fail as it will unable to find hash table cache on RS2 for processing regions

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