The stack trace shows that the OOM error is happening when the distinct is being applied. It looks like in some record(s) of the relation group_it, one more of the following bags is very large - logic.c_users, logic.nc_users or logic.registered_users;
Try setting the property pig.cachedbag.memusage to 0.1 or lower ( -Dpig.cachedbag.memusage=0.1 on java command line). It controls the memory used by pig internal bags, including those used by distinct. If that does not work, you can try computing count-distinct for each type of user separately and then combining the result. You might want to have a look at this way of optimizing count-distinct queries where skew can be a problem - https://issues.apache.org/jira/browse/PIG-1846 -thejas On 5/12/11 10:43 AM, "sonia gehlot" <[email protected]> wrote: > Hi Guys, > > I am running following Pig script in Pig 0.8 version > > page_events = LOAD '/user/sgehlot/day=2011-05-10' as > (event_dt_ht:chararray,event_dt_ut:chararray,event_rec_num:int,event_type:int, > client_ip_addr:long,hub_id:int,is_cookied_user:int,local_ontology_node_id:int, > page_type_id:int,content_id:int,product_id:int,referrer_edition_id:int,page_nu > mber:int,is_iab_robot:int,browser_id:int,os_id:int,dw_pubsys_id:int,refresh:in > t,asset_id:int,asset_type_id:int,content_type_id:int,product_type_id:int,outbo > und_email_id:long,gbal_clc:int,mtype:int,user_action_id:int,referring_partner_ > id:int,ontology_node_id:int,content_namespace_id:int,product_namespace_id:int, > transparent_edition_id:int,default_edition_id:int,event_seq_num:int,is_last_pa > ge:int,is_new_user:int,page_duration:int,page_seq_num:int,session_id:long,time > _since_sess_start:int,reg_cookie:chararray,urs_app_id:int,is_reg_user:int,edit > ion_id:int,user_agent_id:int,page_type_key:int,referrer_id:int,channel_id:int, > level2_id:int,level3_id:int,brand_id:int,content_key:int,product_key:int,editi > on_key:int,partner_key:int,business_unit_id:int,anon_cookie:chararray,machine_ > name:chararray,pagehost:chararray,filenameextension:chararray,referrerpath:cha > rarray,referrerhost:chararray,referring_oid:chararray,referring_legacy_oid:cha > rarray,ctype:chararray,cval:chararray,link_tag:chararray,link_type:chararray,s > ticky_tag:chararray,page_url:chararray,search_category:chararray,partner_subje > ct:chararray,referring_partner_name:chararray,robot_pattern:chararray,browser: > chararray,browser_major_version:chararray,browser_minor_version:chararray,os:c > hararray,os_family:chararray,ttag:chararray,dest_oid:chararray,global_id:chara > rray,hostname:chararray,path:chararray,filename:chararray,extension:chararray, > query:chararray,user_agent:chararray,xrq:chararray,xref:chararray,page_guid:ch > ararray,test_name:chararray,test_group:chararray,test_version:chararray,page_v > ersion:chararray,o_sticky_tag:chararray,new_referring_oid:chararray,day:charar > ray,network_ip:int,site_id:int,search_phrase:chararray,search_attributes:chara > rray,web_search_phrase:chararray,ip_address:chararray,is_pattern_match_robot:i > nt,protocol:chararray,skc_title:chararray,skc_url:chararray,has_site_search_ph > rase:int,has_site_search_attribs:int,has_web_search_phrase:int,title_id:charar > ray,url_id:chararray,network_rev:int); > > referrer_group_map = LOAD '/user/sgehlot/oozie/db_data/referrer_group_map' > as > (referrer_id:int, has_web_search_phrase:int, hostname:chararray, > referral_type_id:int, > referral_type_name:chararray, > referrer_group_id:int,referrer_group_name:chararray,referrer_group_cat_id:int, > referrer_group_cat:chararray); > > filter_pe = FILTER page_events BY is_iab_robot == 0 AND > is_pattern_match_robot == 0 AND day == '2011-05-10'; > > select_pe_col = FOREACH filter_pe GENERATE day, is_cookied_user, > anon_cookie, reg_cookie, referrer_id, has_web_search_phrase, > business_unit_id; > > select_ref_col = FOREACH referrer_group_map GENERATE referrer_id, > has_web_search_phrase, referral_type_id; > > jn = JOIN select_ref_col BY (referrer_id, has_web_search_phrase), > select_pe_col BY (referrer_id, has_web_search_phrase); > > > logic = FOREACH jn GENERATE > select_pe_col::day, > select_ref_col::referral_type_id, > select_pe_col::business_unit_id, > ((select_pe_col::is_cookied_user == 1) ? select_pe_col::anon_cookie : null) > as c_users, > ((select_pe_col::is_cookied_user == 0) ? select_pe_col::anon_cookie : null) > as nc_users, > ((select_pe_col::reg_cookie == '-1') ? null : select_pe_col::reg_cookie) as > registered_users; > group_it = GROUP logic BY (select_pe_col::day, > select_ref_col::referral_type_id, > select_pe_col::business_unit_id); > > agg_results = FOREACH group_it{ > dst_c_users = DISTINCT logic.c_users; > dst_nc_users = DISTINCT logic.nc_users; > dst_registered_users = DISTINCT logic.registered_users; > GENERATE > group.select_pe_col::day, > group.select_ref_col::referral_type_id, > group.select_pe_col::business_unit_id, > COUNT(dst_c_users) as c_users, > COUNT(dst_nc_users) as nc_users, > COUNT(dst_registered_users) as registered_users; > }; > > STORE agg_results INTO '/user/sgehlot/pt_users_referral_type_bu_day' USING > PigStorage('\t'); > > > But I am keep on failing because of Java out of memory error. Data set in > "page_events" is huge but in "referrer_group_map" is relatively very less. > > Here is error message: > > Error: java.lang.OutOfMemoryError: GC overhead limit exceeded > at java.util.ArrayList.(ArrayList.java:112) > at java.util.ArrayList.(ArrayList.java:119) > at org.apache.pig.data.DefaultTuple.(DefaultTuple.java:59) > at org.apache.pig.data.BinSedesTuple.(BinSedesTuple.java:73) > at > org.apache.pig.data.BinSedesTupleFactory.newTuple(BinSedesTupleFactory.java:33> ) > at > org.apache.pig.data.InternalCachedBag$CachedBagIterator.hasNext(InternalCached > Bag.java:236) > at > org.apache.pig.builtin.Distinct.getDistinctFromNestedBags(Distinct.java:136) > at org.apache.pig.builtin.Distinct.access$200(Distinct.java:38) > at org.apache.pig.builtin.Distinct$Intermediate.exec(Distinct.java:101) > at org.apache.pig.builtin.Distinct$Intermediate.exec(Distinct.java:94) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperator > s.POUserFunc.getNext(POUserFunc.java:216) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperator > s.POUserFunc.getNext(POUserFunc.java:253) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.g > etNext(PhysicalOperator.java:334) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator > s.POForEach.processPlan(POForEach.java:332) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator > s.POForEach.getNext(POForEach.java:284) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.p > rocessInput(PhysicalOperator.java:290) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator > s.POLocalRearrange.getNext(POLocalRearrange.java:256) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.processOnePackageOutput(PigCombiner.java:184) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.reduce(PigCombiner.java:162) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.reduce(PigCombiner.java:51) > at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176) > at org.apache.hadoop.mapred.Task$NewCombinerRunner.combine(Task.java:1222) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:126 > 5) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:686) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java: > 1173) > > Error: java.lang.OutOfMemoryError: Java heap space > at java.util.ArrayList.(ArrayList.java:112) > at java.util.ArrayList.(ArrayList.java:119) > at org.apache.pig.data.DefaultDataBag.(DefaultDataBag.java:54) > at > org.apache.pig.data.DefaultBagFactory.newDefaultBag(DefaultBagFactory.java:33) > at org.apache.pig.data.BinInterSedes.readBag(BinInterSedes.java:143) > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:275) > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:251) > at org.apache.pig.data.BinInterSedes.readTuple(BinInterSedes.java:111) > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:270) > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:251) > at org.apache.pig.data.BinInterSedes.addColsToTuple(BinInterSedes.java:555) > at org.apache.pig.data.BinSedesTuple.readFields(BinSedesTuple.java:64) > at > org.apache.pig.impl.io.PigNullableWritable.readFields(PigNullableWritable.java > :114) > at > org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.des > erialize(WritableSerialization.java:67) > at > org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.des > erialize(WritableSerialization.java:40) > at > org.apache.hadoop.mapreduce.ReduceContext.nextKeyValue(ReduceContext.java:116) > at > org.apache.hadoop.mapreduce.ReduceContext$ValueIterator.next(ReduceContext.jav > a:163) > at > org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator > s.POCombinerPackage.getNext(POCombinerPackage.java:141) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.processOnePackageOutput(PigCombiner.java:171) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.reduce(PigCombiner.java:162) > at > org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi > ne.reduce(PigCombiner.java:51) > at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176) > at org.apache.hadoop.mapred.Task$NewCombinerRunner.combine(Task.java:1222) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:126 > 5) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:686) > at > org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java: > 1173) > > Any idea and suggestion what could be cause of error message? > > Thanks for any help, > Sonia > --
