hbase-logroll optimizations

 

  as u know,the hbas's data logs (akka wal) will roll after certain intervals to speedup restore data lost occasionally.and of course,both log rolling and flush memstore will block up all wirtes but reads.so if decreasing the log rolling will optimize the cluster perf.

 

1.case

  during the high load period of a day,some ugly logs are occured as below:

2015-09-07 09:10:35,380 WARN [IPC Server handler 1 on 60020] WritableRpcEngine.java:436 (responseTooSlow): {"processingtimems":22896,"call":"multi(org.apache.hadoop.hbase.client.Mul
tiAction@72e76446), rpc version=1, client version=29, methodsFingerPrint=-56040613","client":"192.168.0.117:55979","starttimems":1441588212481,"queuetimems":0,"class":"HRegionServer
","responsesize":0,"method":"multi"}
2015-09-07 09:11:45,033 DEBUG [regionserver60020.logRoller] LogRoller.java:86 Hlog roll period 3600000ms elapsed
2015-09-07 09:11:45,033 INFO [regionserver60020.logRoller] FSUtils.java:429 FileSystem doesn't support getDefaultReplication
2015-09-07 09:11:45,034 INFO [regionserver60020.logRoller] FSUtils.java:395 FileSystem doesn't support getDefaultBlockSize
2015-09-07 09:11:45,037 DEBUG [regionserver60020.logRoller] SequenceFileLogWriter.java:195 using new createWriter -- HADOOP-6840
2015-09-07 09:11:45,037 DEBUG [regionserver60020.logRoller] SequenceFileLogWriter.java:208 Path=hdfs://hd02:54310/hbase-94s/.logs/node-59,60020,1441098691966/node-59%2C60020%2C14410
98691966.1441588305033, syncFs=true, hflush=false, compression=false
2015-09-07 09:11:45,053 INFO [regionserver60020.logRoller] HLog.java:654 Roll /hbase-94s/.logs/node-59,60020,1441098691966/node-59%2C60020%2C1441098691966.1441584704954, entries=123
01, filesize=25620076.  for /hbase-94s/.logs/node-59,60020,1441098691966/node-59%2C60020%2C1441098691966.1441588305033
2015-09-07 09:11:46,104 DEBUG [LRU Statistics #0] LruBlockCache.java:681 Stats: total=1.37 GB, free=2.32 GB, max=3.69 GB, blocks=10745, accesses=22326231, hits=19423914, hitRatio=87
.00%, , cachingAccesses=19369432, cachingHits=19352868, cachingHitsRatio=99.91%, , evictions=0, evicted=5776, evictedPerRun=Infinity
2015-09-07 09:12:05,535 WARN [IPC Server handler 0 on 60020] WritableRpcEngine.java:436 (responseTooSlow): {"processingtimems":17071,"call":"multi(org.apache.hadoop.hbase.client.Mul
tiAction@1ef7f77), rpc version=1, client version=29, methodsFingerPrint=-56040613","client":"192.168.0.142:44554","starttimems":1441588308460,"queuetimems":0,"class":"HRegionServer"
,"responsesize":0,"method":"multi"}
2015-09-07 09:12:42,259 INFO [regionserver60020-SendThread(node-01:2181)] ClientCnxn.java:1085 Unable to read additional data from server sessionid 0x14dd790d3735f22, likely server 
has closed socket, closing socket connection and attempting reconnect

 

 

2.optimizations

1) compress the logs by compress option to reduce io

hbase.regionserver.wal.enablecompression=true

 

   the principle of it pls check out LRUDiction.java

   before:

2015-09-17 03:32:52,361 INFO [regionserver60020.logRoller] HLog.java:654 Roll /hbase/.logs/node-app-13,60020,1441852998783/node-app-13%2C60020%2C1441852998783.1442429970301, entries
=54994, filesize=127512793.  for /hbase/.logs/node-app-13,60020,1441852998783/node-app-13%2C60020%2C1441852998783.1442431972113

   now:

2015-09-22 08:22:04,008 INFO [regionserver60020.logRoller] HLog.java:654 Roll /hbase/.logs/node-app-13,60020,1442683680803/node-app-13%2C60020%2C1442683680803.1442877723854, entries
=34246, filesize=45448938.  for /hbase/.logs/node-app-13,60020,1442683680803/node-app-13%2C60020%2C1442683680803.1442881323960

   so the compress ratio per entry is:

   (45448938/34246 ) / (127512793 / 54994) ~ 0.6

   that is 40 percent of raw spaces are saved,it's very considerable to derive that.

   in additional,these logs are needless to decompress generally,beside that some rs downs occasionally.

 

2) memory data compress

 TBD

 

3) increase the hlog block size

to delay compression

hbase.regionserver.hlog.blocksize=<should-more-then-dfs's one>

   now i give  a double dfs block size to that:268435456

  hbase will not occupy some more memory though i set it more then default(dfs size)

 

4) increase the log roll interval

   either this case or 3) will occur by which comes first,so i will set it to 10 hours:36000000