Sorry I had pressed Control + Enter a little earlier than I wanted to, corrections inline. Thanks
From: "Thangamani, Arun" <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Tuesday, February 16, 2016 at 8:38 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Cc: James Taylor <[email protected]<mailto:[email protected]>>, Lars Hofhansl <[email protected]<mailto:[email protected]>> Subject: Re: Write path blocked by MetaDataEndpoint acquiring region lock Hey Nick, Looks like you are failing to find your table in meta data cache, if you don’t find it in the meta data cache, we end up rebuilding the metadata from both the SYSTEM.CATALOG and SYSTEM.STATS tables. The rebuilding process for the meta data is a scan on both the tables. So, we will end up going to zookeeper to find the region and execute the scan on the region, it is an expensive operation, that explains the calls to a specific region server and zookeeper Similar thing happens in PHOENIX-2607, but that is specifiically related to timestamps, if the client timestamp is less than or equal to the stats timestamp of the table, we will end up doing the above rebuilding process repeatedly for every batch of insert from PhoenixMapReduceUtil (Batch size default is 1000 rows). I don’t believe you have a timestamp issue, but looks like you have the same repeated lookups and related scans for rebuilding that happen in PHOENIX-2607 James has suggested a workaround for the meta data cache refresh using UPDATE_CACHE_FREQUENCY variable while defining the table, and it will probably help (we are trying it out for timestamp issue) Hope this helps. Thanks Arun Please look at the following lines in MetadataCacheImpl private PTable doGetTable(byte[] key, long clientTimeStamp, RowLock rowLock) throws IOException, SQLException { ImmutableBytesPtr cacheKey = new ImmutableBytesPtr(key); Cache<ImmutableBytesPtr, PMetaDataEntity> metaDataCache = GlobalCache.getInstance(this.env).getMetaDataCache(); PTable table = (PTable)metaDataCache.getIfPresent(cacheKey); // We only cache the latest, so we'll end up building the table with every call if the // client connection has specified an SCN. // TODO: If we indicate to the client that we're returning an older version, but there's a // newer version available, the client // can safely not call this, since we only allow modifications to the latest. if (table != null && table.getTimeStamp() < clientTimeStamp) { // Table on client is up-to-date with table on server, so just return if (isTableDeleted(table)) { return null; } return table; } // Ask Lars about the expense of this call - if we don't take the lock, we still won't get // partial results // get the co-processor environment // TODO: check that key is within region.getStartKey() and region.getEndKey() // and return special code to force client to lookup region from meta. Region region = env.getRegion(); /* * Lock directly on key, though it may be an index table. This will just prevent a table * from getting rebuilt too often. */ final boolean wasLocked = (rowLock != null); if (!wasLocked) { rowLock = region.getRowLock(key, true); if (rowLock == null) { throw new IOException("Failed to acquire lock on " + Bytes.toStringBinary(key)); } } try { // Try cache again in case we were waiting on a lock table = (PTable)metaDataCache.getIfPresent(cacheKey); // We only cache the latest, so we'll end up building the table with every call if the // client connection has specified an SCN. // TODO: If we indicate to the client that we're returning an older version, but there's // a newer version available, the client // can safely not call this, since we only allow modifications to the latest. if (table != null && table.getTimeStamp() < clientTimeStamp) { // Table on client is up-to-date with table on server, so just return if (isTableDeleted(table)) { return null; } return table; } // Query for the latest table first, since it's not cached table = buildTable(key, cacheKey, region, HConstants.LATEST_TIMESTAMP); if (table != null && table.getTimeStamp() < clientTimeStamp) { return table; } // Otherwise, query for an older version of the table - it won't be cached return buildTable(key, cacheKey, region, clientTimeStamp); } finally { if (!wasLocked) rowLock.release(); } } From: Nick Dimiduk <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Tuesday, February 16, 2016 at 5:58 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Cc: James Taylor <[email protected]<mailto:[email protected]>>, Lars Hofhansl <[email protected]<mailto:[email protected]>> Subject: Write path blocked by MetaDataEndpoint acquiring region lock Hello, I have a high throughput ingest pipeline that's seised up. My ingest application ultimately crashes, contains the following stack trace [0]. Independently, I noticed that the RPC call time of one of the machines was significantly higher than others (95pct at multiple seconds vs 10's of ms). I grabbed the RS log and a couple jstacks from the process. In the logs I see handler threads creating ZK connections excessively (~50 INFO lines per second). The jstacks show handler threads parked while taking region row locks, calling HRegion.getRowLockInternal() via MetaDataEndpointImpl.doGetTable() [1]. The one handler thread I see that's in the same MetaDataEndpointImpl area but not under lock appears to be making an RPC to read the statistics table [2]. I believe these two occurrences are related. My working theory is that the metaDataCache object is performing poorly for some reason. This results in excessive meta data lookups, some of which appear to require making an RPC call while under lock. What can I do to relive pressure on this rowlock? Looking at the code around the lock, this looks like it's populating to a connection-level cache of schema metadata. The host with the high RPC call time is hosting the SYSTEM.CATALOG table region. I see some configuration settings that may be related (ie, phoenix.coprocessor.maxMetaDataCacheSize), but I see no way to get debug information about cache size or evictions from this Guava cache instance. I'll be digging into this further, but I appreciate any pointers you may have. BTW, this is Phoenix 4.6.0 + HBase 1.1.2. Thanks a lot, -n [0]: client-side stack Caused by: org.apache.phoenix.exception.PhoenixIOException: Interrupted calling coprocessor service org.apache.phoenix.coprocessor.generated.MetaDataProtos$MetaDataService for row \x00<schema>\x00<user_table> at org.apache.phoenix.util.ServerUtil.parseServerException(ServerUtil.java:108) at org.apache.phoenix.query.ConnectionQueryServicesImpl.metaDataCoprocessorExec(ConnectionQueryServicesImpl.java:1053) at org.apache.phoenix.query.ConnectionQueryServicesImpl.metaDataCoprocessorExec(ConnectionQueryServicesImpl.java:1016) at org.apache.phoenix.query.ConnectionQueryServicesImpl.getTable(ConnectionQueryServicesImpl.java:1289) at org.apache.phoenix.schema.MetaDataClient.updateCache(MetaDataClient.java:446) at org.apache.phoenix.schema.MetaDataClient.updateCache(MetaDataClient.java:389) at org.apache.phoenix.schema.MetaDataClient.updateCache(MetaDataClient.java:385) at org.apache.phoenix.execute.MutationState.validate(MutationState.java:369) at org.apache.phoenix.execute.MutationState.commit(MutationState.java:417) at org.apache.phoenix.jdbc.PhoenixConnection$3.call(PhoenixConnection.java:482) at org.apache.phoenix.jdbc.PhoenixConnection$3.call(PhoenixConnection.java:479) at org.apache.phoenix.call.CallRunner.run(CallRunner.java:53) at org.apache.phoenix.jdbc.PhoenixConnection.commit(PhoenixConnection.java:479) at org.apache.phoenix.mapreduce.PhoenixRecordWriter.write(PhoenixRecordWriter.java:84) [1] rs handlers blocked stack "B.defaultRpcServer.handler=48,queue=3,port=16020" #91 daemon prio=5 os_prio=0 tid=0x00007ff4ce458000 nid=0xca0a waiting on condition [0x00007ff47a607000] java.lang.Thread.State: TIMED_WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for <0x0000000708ef59c0> (a java.util.concurrent.CountDownLatch$Sync) at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215) at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java:1037) at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1328) at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:277) at org.apache.hadoop.hbase.regionserver.HRegion.getRowLockInternal(HRegion.java:5047) at org.apache.hadoop.hbase.regionserver.HRegion.getRowLock(HRegion.java:5013) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.doGetTable(MetaDataEndpointImpl.java:2397) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.doGetTable(MetaDataEndpointImpl.java:2365) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.getTable(MetaDataEndpointImpl.java:440) at org.apache.phoenix.coprocessor.generated.MetaDataProtos$MetaDataService.callMethod(MetaDataProtos.java:11609) at org.apache.hadoop.hbase.regionserver.HRegion.execService(HRegion.java:7435) at org.apache.hadoop.hbase.regionserver.RSRpcServices.execServiceOnRegion(RSRpcServices.java:1875) at org.apache.hadoop.hbase.regionserver.RSRpcServices.execService(RSRpcServices.java:1857) at org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:32209) at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2114) at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:101) at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:130) at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:107) at java.lang.Thread.run(Thread.java:745) [2]: rs handler stats rpc stack "B.defaultRpcServer.handler=19,queue=4,port=16020" #62 daemon prio=5 os_prio=0 tid=0x00007ff4ce420000 nid=0xc9ea in Object.wait() [0x00007ff47c323000] java.lang.Thread.State: TIMED_WAITING (on object monitor) at java.lang.Object.wait(Native Method) at java.lang.Object.wait(Object.java:460) at java.util.concurrent.TimeUnit.timedWait(TimeUnit.java:348) at org.apache.hadoop.hbase.client.ResultBoundedCompletionService.poll(ResultBoundedCompletionService.java:155) - locked <0x00000007a3f5e030> (a [Lorg.apache.hadoop.hbase.client.ResultBoundedCompletionService$QueueingFuture;) at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:168) at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:59) at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:200) at org.apache.hadoop.hbase.client.ClientScanner.call(ClientScanner.java:320) at org.apache.hadoop.hbase.client.ClientScanner.loadCache(ClientScanner.java:403) at org.apache.hadoop.hbase.client.ClientScanner.next(ClientScanner.java:364) at org.apache.phoenix.schema.stats.StatisticsUtil.readStatistics(StatisticsUtil.java:99) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.getTable(MetaDataEndpointImpl.java:836) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.buildTable(MetaDataEndpointImpl.java:472) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.doGetTable(MetaDataEndpointImpl.java:2418) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.doGetTable(MetaDataEndpointImpl.java:2365) at org.apache.phoenix.coprocessor.MetaDataEndpointImpl.getTable(MetaDataEndpointImpl.java:440) at org.apache.phoenix.coprocessor.generated.MetaDataProtos$MetaDataService.callMethod(MetaDataProtos.java:11609) at org.apache.hadoop.hbase.regionserver.HRegion.execService(HRegion.java:7435) at org.apache.hadoop.hbase.regionserver.RSRpcServices.execServiceOnRegion(RSRpcServices.java:1875) at org.apache.hadoop.hbase.regionserver.RSRpcServices.execService(RSRpcServices.java:1857) at org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:32209) at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2114) at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:101) at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:130) at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:107) at java.lang.Thread.run(Thread.java:745) ________________________________ This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. 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