Turn the logging up in cassandra or your MR job and make sure the batch_mutation is sent. Sounds like it's not.
Cheers ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 12 Aug 2011, at 07:22, Jian Fang wrote: > 53 seconds included the map phase to read and process the input file. The > records were updated at the end of the reduce phase. > > I checked the sales ranks in the update file and the sales ranks in the > Cassandra, they are different and thus, the records > were not actually updated. > > I remember I run the word count example for Cassandra 0.8.0 some time ago, I > saw the similar behavior, i.e., the results were not written to the Cassandra > column family. But If I changed hadoop to write to the file system, I can see > the results in the output file. I didn't try the word count example for > Cassandra 0.8.2 though. > > Anyway to solve this problem? > > Thanks, > > John > On Thu, Aug 11, 2011 at 12:17 AM, aaron morton <aa...@thelastpickle.com> > wrote: > I'm a simple guy. My first step would be see if the expected data is in the > data base, if not what's missing. > > 2.5M updates / 3 nodes = 833,333 per node > 833,333 / 53 seconds = 15,723 per second > 1 / 15,723 = 0.00006 seconds / 0.06 milliseconds per mutation > > sounds reasonable to me. > > check the Write Latency in nodetool cfstats and the row count estimates. > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > > On 11 Aug 2011, at 14:50, Jian Fang wrote: > >> There are data and each Cassandra cluster node holds about 100G. From the >> application point of view, if I run the job twice with the same input file, >> i.e., the sales rank update file, then I should see a much smaller number of >> products, whose rank change exceeds the threshold, in the output file for >> the second run because the sales ranks have been updated to be the same as >> the ranks in the input file during the first run. But actually, I saw the >> output files stay the same for the two runs. One explanation is that the >> ranks were not actually updated for the first run. Also, 53 seconds to run >> the whole hadoop job with 2.5 million Cassandra updates on three nodes, do >> you think that is possible? Each node is a regular Linux box with 8 CPUs. >> >> Thanks, >> >> John >> >> On Wed, Aug 10, 2011 at 5:40 PM, aaron morton <aa...@thelastpickle.com> >> wrote: >>> Seems the data are not actually written to Cassandra. >> >> Before jumping into the Hadoop side of things are you saying there is no >> data in Cassandra ? Can you retrieve any using the CLI ? Take a look at >> cfstats on each node to see the estimated record count. >> >> Cheers >> >> ----------------- >> Aaron Morton >> Freelance Cassandra Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 11 Aug 2011, at 08:20, Jian Fang wrote: >> >>> Hi, >>> >>> I am using Cassandra 0.8.2 with Hadoop 0.20.2. My application read a file >>> and then write about 2.5 million records >>> to Cassandra. I used ColumnFamilyOutputFormat to write to Cassandra. My >>> Cassandra cluster has three nodes with >>> one Hadoop task tracker on each node. The wired problem is that I only saw >>> one map and one reducer tasks and job only took >>> 53 seconds to finish. Seems the data are not actually written to Cassandra. >>> >>> Here is status from Hadoop web admin: >>> >>> User: hadoop >>> Job Name: SalesRankWriter >>> Job File: >>> hdfs://xxxxx:54310/hadoop/tmp/mapred/system/job_201108051329_0060/job.xml >>> Job Setup: Successful >>> Status: Succeeded >>> Started at: Wed Aug 10 15:24:43 EDT 2011 >>> Finished at: Wed Aug 10 15:25:36 EDT 2011 >>> Finished in: 52sec >>> Job Cleanup: Successful >>> Kind % Complete Num Tasks Pending Running Complete >>> Killed Failed/Killed >>> Task Attempts >>> map 100.00% >>> 1 0 0 1 0 0 / 0 >>> reduce 100.00% >>> 1 0 0 1 0 0 / 0 >>> >>> Counter Map Reduce Total >>> Job Counters Launched reduce tasks 0 0 1 >>> Launched map tasks 0 0 1 >>> Data-local map tasks 0 0 1 >>> FileSystemCounters FILE_BYTES_READ 50,698,700 50,698,646 >>> 101,397,346 >>> HDFS_BYTES_READ 56,149,360 0 56,149,360 >>> FILE_BYTES_WRITTEN 101,397,378 50,698,646 152,096,024 >>> Map-Reduce Framework Reduce input groups 0 2,534,932 >>> 2,534,932 >>> Combine output records 0 0 0 >>> Map input records 2,534,932 0 2,534,932 >>> Reduce shuffle bytes 0 0 0 >>> Reduce output records 0 2,534,932 2,534,932 >>> Spilled Records 5,069,864 2,534,932 7,604,796 >>> Map output bytes 45,628,776 0 45,628,776 >>> Map output records 2,534,932 0 2,534,932 >>> Combine input records 0 0 0 >>> Reduce input records 0 2,534,932 2,534,932 >>> >>> and the log for the mapper >>> >>> 2011-08-10 15:24:48,717 INFO org.apache.hadoop.metrics.jvm.JvmMetrics: >>> Initializing JVM Metrics with processName=MAP, sessionId= >>> 2011-08-10 15:24:48,857 INFO org.apache.hadoop.mapred.MapTask: io.sort.mb = >>> 100 >>> 2011-08-10 15:24:48,917 INFO org.apache.hadoop.mapred.MapTask: data buffer >>> = 79691776/99614720 >>> 2011-08-10 15:24:48,917 INFO org.apache.hadoop.mapred.MapTask: record >>> buffer = 262144/327680 >>> 2011-08-10 15:24:49,760 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:49,760 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 0; bufend = 4718592; bufvoid = 99614720 >>> 2011-08-10 15:24:49,760 INFO org.apache.hadoop.mapred.MapTask: kvstart = 0; >>> kvend = 262144; length = 327680 >>> 2011-08-10 15:24:50,364 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 0 >>> 2011-08-10 15:24:50,707 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:50,707 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 4718592; bufend = 9437166; bufvoid = 99614720 >>> 2011-08-10 15:24:50,707 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 262144; kvend = 196607; length = 327680 >>> 2011-08-10 15:24:51,238 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 1 >>> 2011-08-10 15:24:51,583 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:51,583 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 9437166; bufend = 14155740; bufvoid = 99614720 >>> 2011-08-10 15:24:51,583 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 196607; kvend = 131070; length = 327680 >>> 2011-08-10 15:24:52,084 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 2 >>> 2011-08-10 15:24:52,433 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:52,433 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 14155740; bufend = 18874314; bufvoid = 99614720 >>> 2011-08-10 15:24:52,433 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 131070; kvend = 65533; length = 327680 >>> 2011-08-10 15:24:52,877 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 3 >>> 2011-08-10 15:24:53,216 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:53,216 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 18874314; bufend = 23592906; bufvoid = 99614720 >>> 2011-08-10 15:24:53,216 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 65533; kvend = 327677; length = 327680 >>> 2011-08-10 15:24:53,660 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 4 >>> 2011-08-10 15:24:54,010 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:54,010 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 23592906; bufend = 28311480; bufvoid = 99614720 >>> 2011-08-10 15:24:54,010 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 327677; kvend = 262140; length = 327680 >>> 2011-08-10 15:24:54,447 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 5 >>> 2011-08-10 15:24:54,793 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:54,793 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 28311480; bufend = 33030054; bufvoid = 99614720 >>> 2011-08-10 15:24:54,793 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 262140; kvend = 196603; length = 327680 >>> 2011-08-10 15:24:55,237 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 6 >>> 2011-08-10 15:24:55,564 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:55,564 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 33030054; bufend = 37748628; bufvoid = 99614720 >>> 2011-08-10 15:24:55,564 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 196603; kvend = 131066; length = 327680 >>> 2011-08-10 15:24:55,981 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 7 >>> 2011-08-10 15:24:56,434 INFO org.apache.hadoop.mapred.MapTask: Spilling map >>> output: record full = true >>> 2011-08-10 15:24:56,434 INFO org.apache.hadoop.mapred.MapTask: bufstart = >>> 37748628; bufend = 42467202; bufvoid = 99614720 >>> 2011-08-10 15:24:56,434 INFO org.apache.hadoop.mapred.MapTask: kvstart = >>> 131066; kvend = 65529; length = 327680 >>> 2011-08-10 15:24:56,848 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 8 >>> 2011-08-10 15:24:57,051 INFO org.apache.hadoop.mapred.MapTask: Starting >>> flush of map output >>> 2011-08-10 15:24:57,282 INFO org.apache.hadoop.mapred.MapTask: Finished >>> spill 9 >>> 2011-08-10 15:24:57,291 INFO org.apache.hadoop.mapred.Merger: Merging 10 >>> sorted segments >>> 2011-08-10 15:24:57,297 INFO org.apache.hadoop.mapred.Merger: Down to the >>> last merge-pass, with 10 segments left of total size: 50698660 bytes >>> 2011-08-10 15:24:59,552 INFO org.apache.hadoop.mapred.TaskRunner: >>> Task:attempt_201108051329_0060_m_000000_0 is done. And is in the process of >>> commiting >>> 2011-08-10 15:24:59,555 INFO org.apache.hadoop.mapred.TaskRunner: Task >>> 'attempt_201108051329_0060_m_000000_0' done. >>> >>> and the log for the reducer >>> >>> 2011-08-10 15:25:00,835 INFO org.apache.hadoop.metrics.jvm.JvmMetrics: >>> Initializing JVM Metrics with processName=SHUFFLE, sessionId= >>> 2011-08-10 15:25:01,005 INFO org.apache.hadoop.mapred.ReduceTask: >>> ShuffleRamManager: MemoryLimit=140699232, MaxSingleShuffleLimit=35174808 >>> 2011-08-10 15:25:01,022 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Thread started: Thread for merging >>> on-disk files >>> 2011-08-10 15:25:01,022 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Thread started: Thread for merging in >>> memory files >>> 2011-08-10 15:25:01,022 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Thread waiting: Thread for merging >>> on-disk files >>> 2011-08-10 15:25:01,024 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Need another 1 map output(s) where 0 >>> is already in progress >>> 2011-08-10 15:25:01,024 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Thread started: Thread for polling Map >>> Completion Events >>> 2011-08-10 15:25:01,037 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Scheduled 0 outputs (0 slow hosts and0 >>> dup hosts) >>> 2011-08-10 15:25:01,038 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0: Got 1 new map-outputs >>> 2011-08-10 15:25:06,039 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Scheduled 1 outputs (0 slow hosts and0 >>> dup hosts) >>> 2011-08-10 15:25:06,121 INFO org.apache.hadoop.mapred.ReduceTask: header: >>> attempt_201108051329_0060_m_000000_0, compressed len: 50698646, >>> decompressed len: 50698642 >>> 2011-08-10 15:25:06,121 INFO org.apache.hadoop.mapred.ReduceTask: Shuffling >>> 50698642 bytes (50698646 raw bytes) into Local-FS from >>> attempt_201108051329_0060_m_000000_0 >>> 2011-08-10 15:25:06,314 INFO org.apache.hadoop.mapred.ReduceTask: Read >>> 50698646 bytes from map-output for attempt_201108051329_0060_m_000000_0 >>> 2011-08-10 15:25:06,315 INFO org.apache.hadoop.mapred.ReduceTask: >>> attempt_201108051329_0060_r_000000_0 Thread waiting: Thread for merging >>> on-disk files >>> 2011-08-10 15:25:07,055 INFO org.apache.hadoop.mapred.ReduceTask: >>> GetMapEventsThread exiting >>> 2011-08-10 15:25:07,055 INFO org.apache.hadoop.mapred.ReduceTask: >>> getMapsEventsThread joined. >>> 2011-08-10 15:25:07,056 INFO org.apache.hadoop.mapred.ReduceTask: Closed >>> ram manager >>> 2011-08-10 15:25:07,056 INFO org.apache.hadoop.mapred.ReduceTask: >>> Interleaved on-disk merge complete: 1 files left. >>> 2011-08-10 15:25:07,056 INFO org.apache.hadoop.mapred.ReduceTask: In-memory >>> merge complete: 0 files left. >>> 2011-08-10 15:25:07,061 INFO org.apache.hadoop.mapred.ReduceTask: Merging 1 >>> files, 50698646 bytes from disk >>> 2011-08-10 15:25:07,062 INFO org.apache.hadoop.mapred.ReduceTask: Merging 0 >>> segments, 0 bytes from memory into reduce >>> 2011-08-10 15:25:07,065 INFO org.apache.hadoop.mapred.Merger: Merging 1 >>> sorted segments >>> 2011-08-10 15:25:07,072 INFO org.apache.hadoop.mapred.Merger: Down to the >>> last merge-pass, with 1 segments left of total size: 50698642 bytes >>> 2011-08-10 15:25:30,126 INFO org.apache.hadoop.mapred.TaskRunner: >>> Task:attempt_201108051329_0060_r_000000_0 is done. And is in the process of >>> commiting >>> 2011-08-10 15:25:30,129 INFO org.apache.hadoop.mapred.TaskRunner: Task >>> 'attempt_201108051329_0060_r_000000_0' done. >>> >>> My code is similar to the word count example: >>> >>> public int run(String[] args) throws Exception { >>> ... >>> >>> getConf().set(CONF_COLUMN_NAME, columnName); >>> >>> Job job4 = new Job(getConf(), "SalesRankWriter"); >>> job4.setJarByClass(SalesRankLoader.class); >>> job4.setMapperClass(RankUpdateMapper.class); >>> job4.setReducerClass(RankUpdateReducer.class); >>> job4.setMapOutputKeyClass(Text.class); >>> job4.setMapOutputValueClass(IntWritable.class); >>> job4.setOutputKeyClass(ByteBuffer.class); >>> job4.setOutputValueClass(List.class); >>> job4.setOutputFormatClass(ColumnFamilyOutputFormat.class); >>> job4.setInputFormatClass(TextInputFormat.class); >>> FileInputFormat.addInputPath(job4, new Path(prePath)); >>> >>> ConfigHelper.setOutputColumnFamily(job4.getConfiguration(), >>> KEYSPACE, columnFamily); >>> ConfigHelper.setRpcPort(job4.getConfiguration(), "9260"); >>> ConfigHelper.setInitialAddress(job4.getConfiguration(), >>> "dnjsrcha01"); >>> ConfigHelper.setPartitioner(job4.getConfiguration(), >>> "org.apache.cassandra.dht.RandomPartitioner"); >>> >>> >>> job4.waitForCompletion(true); >>> ... >>> } >>> >>> >>> >>> >>> where the mapper and reducer are defined as: >>> >>> public static class RankUpdateMapper extends Mapper<LongWritable, Text, >>> Text, IntWritable> { >>> public void map(LongWritable key, Text value, Context context) >>> throws IOException, InterruptedException { >>> String line = value.toString(); >>> StringTokenizer tokenizer = new StringTokenizer(line); >>> String ean = tokenizer.nextToken(); >>> int rank = Integer.parseInt(tokenizer.nextToken()); >>> >>> context.write(new Text(ean), new IntWritable(rank)); >>> } >>> } >>> >>> public static class RankUpdateReducer extends Reducer<Text, >>> IntWritable, ByteBuffer, List<Mutation>> >>> { >>> private ByteBuffer outputKey; >>> >>> protected void setup(org.apache.hadoop.mapreduce.Reducer.Context >>> context) throws IOException, InterruptedException >>> { >>> outputKey = >>> ByteBufferUtil.bytes(context.getConfiguration().get(CONF_COLUMN_NAME)); >>> } >>> >>> public void reduce(Text key, Iterable<IntWritable> values, Context >>> context) throws IOException, InterruptedException >>> { >>> context.write(outputKey, >>> Collections.singletonList(getMutation(key, >>> values.iterator().next().get()))); >>> } >>> >>> private static Mutation getMutation(Text key, int value) >>> { >>> Column c = new Column(); >>> c.setName(ByteBuffer.wrap(Arrays.copyOf(key.getBytes(), >>> key.getLength()))); >>> c.setValue(ByteBufferUtil.bytes(String.valueOf(value))); >>> c.setTimestamp(System.currentTimeMillis() * 1000); >>> >>> Mutation m = new Mutation(); >>> m.setColumn_or_supercolumn(new ColumnOrSuperColumn()); >>> m.column_or_supercolumn.setColumn(c); >>> return m; >>> } >>> } >>> >>> Any thing wrong here? >>> >>> Thanks, >>> >>> John >> >> > >
