Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-5627

mongodb hangs when doing mapreduce

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: 2.0.2
    • Fix Version/s: 2.1.2
    • Component/s: JavaScript, MapReduce
    • Labels:
      None
    • Environment:
      Distributor ID: Ubuntu
      Description: Ubuntu 10.04.3 LTS
      Release: 10.04
      Codename: lucid
      Linux data2 2.6.32-33-generic #72-Ubuntu SMP Fri Jul 29 21:07:13 UTC 2011 x86_64 GNU/Linux
    • Operating System:
      Linux

      Description

      mongodb hang this and last weekend when doing mapreduce at the very
      early stage. Following is the related log (i think), the full log is
      at https://gist.github.com/2395867

      The db is fully locked without yield and any collection related operations hang. Deadlock maybe?

      The mapreduce code should be fine. After i restart the mongodb and
      rerun the mapreduce, it finished in less than 10 minutes.

      Following is the log and code. Unfortunately, the mongodb log was lost when i restart mongodb.

      mongostat --port 27018 5
      connected to: 127.0.0.1:27018
      insert  query update delete getmore command flushes mapped  vsize    res faults locked % idx miss %     qr|qw   ar|aw  netIn netOut  conn        set repl       time 
           0      0      0      0       0       1       0    75g   151g   9.1g      0        0          0       5|3     5|2   113b   424b    16 rs_default    M   08:58:12 
           0      0      0      0       0       1       0    75g   151g   9.1g      0        0          0       5|3     5|2   163b   480b    16 rs_default    M   08:58:17 
       
      PRIMARY> db.currentOp()
      {
             "inprog" : [
                     {
                             "opid" : 15710450,
                             "active" : true,
                             "lockType" : "read",
                             "waitingForLock" : true,
                             "secs_running" : 17965,
                             "op" : "getmore",
                             "ns" : "local.oplog.rs",
                             "query" : {
       
                             },
                             "client" : "192.168.0.21:55171",
                             "desc" : "conn",
                             "threadId" : "0x7f1e8d1f3700",
                             "connectionId" : 5,
                             "numYields" : 0
                     },
                     {
                             "opid" : 15710430,
                             "active" : true,
                             "lockType" : "read",
                             "waitingForLock" : false,
                             "secs_running" : 17966,
                             "op" : "query",
                             "ns" : "app_wowsearch.events.day",
                             "query" : {
                                     "$msg" : "query not recording (too large)"
                             },
                             "client" : "127.0.0.1:33900",
                             "desc" : "conn",
                             "threadId" : "0x7f1e8daf5700",
                             "connectionId" : 19963,
                             "msg" : "m/r: (1/3) emit phase 0/835941 0%",
                             "progress" : {
                                     "done" : 0,
                                     "total" : 835941
                             },
                             "numYields" : 3
                     },
       
       
      db.serverStatus()
      {
             "host" : "data2:27018",
             "version" : "2.0.2",
             "process" : "mongod",
             "uptime" : 602434,
             "uptimeEstimate" : 594271,
             "localTime" : ISODate("2012-04-16T00:59:47.391Z"),
             "globalLock" : {
                     "totalTime" : 602434261059,
                     "lockTime" : 56141056582,
                     "ratio" : 0.09319034492379538,
                     "currentQueue" : {
                             "total" : 8,
                             "readers" : 5,
                             "writers" : 3
                     },
                     "activeClients" : {
                             "total" : 7,
                             "readers" : 5,
                             "writers" : 2
                     }
             },

      Here is the map reduce code, a few utility functions are not provided. If you want them, I can provide too.

      function rollup_cycle_users(cycle, firstday) { //{{{
              var m = function() { //{{{
                      var l = this.l || {};
       
                      var mk = {id: this.id, l: {}};
                      var keys = ['s', 'rt', 'rc', 'rf', 'va'];
                      keys.forEach(function(k) {
                              mk.l[k] = l[k] || null;
                      });
       
                      var mv = extend(copy_obj(this, ['model', 'ch', 'city', 'province', 'avn', 'resolution']),
                                      {
                                              pvs: 0,
                                              downloads: 0,
                                              searchs: 0,
                                              video_pls: 0,
                                              days: {},
                                      });
                      var e2dayname = {
                              search: 'sedays',   
                              download: 'dldays', 
                              pv: 'pvdays',       
                              video_play: 'vpdays',
                      };
                      switch(this.e){
                              case 'download' : mv.downloads += this.c || 1; break;
                              case 'pv' : mv.pvs += this.c || 1; break;
                              case 'search' : mv.searchs += this.c || 1; break;
                              case 'video_play' : mv.video_pls += this.c || 1; break;
                      }
                      var day_name = e2dayname[this.e];
                      if (day_name) {
                              var d = 1 + (this.ts.getTime() - base_ts.getTime()) / (24 * 3600000); // start from 1
                              mv.days[day_name] = {};
                              mv.days[day_name][d] = true;
                              emit(mk, mv);       
                      }
              }; //}}}
       
              var r = function(key, emits) { //{{{
                      var total0 = {downloads: 0, pvs: 0, video_pls:0, searchs:0, days: {}};
                      if (emits.length == 0) {    
                              return total0;      
                      }
                      var total = extend(emits[0], total0);
       
                      var tdays = total.days;     
                      emits.forEach(function(emit) {
                              for (day_name in emit.days) {
                                      tdays[day_name] = extend(tdays[day_name] || {}, emit.days[day_name]);
                                      tdays[day_name] = tdays[day_name] || {};
                                      for (d in emit.days[day_name]) {
                                              tdays[day_name][d] = true;
                                      }
                              }
                              total.downloads += emit.downloads;
                              total.pvs += emit.pvs;
                              total.video_pls += emit.video_pls;
                              total.searchs += emit.searchs;
                      });
                      return total;
              }; //}}}
       
              var f = function(key, total) { //{{{
                      function count(days) {      
                              days = days || [];  
                              return days.length; 
                      }
                      function max_continuous_count(days) { //{{{
                              days = days || [];  
                              if (!days.length) return 0;
       
                              var max_ccount = 0; 
                              var ccount = 0;     
                              days = days.concat([-1]); // guard
                              for (i in days) {   
                                      if (days[i] - days[i-1] != 1 || i == 0) {
                                              max_ccount = Math.max(max_ccount, ccount);
                                              ccount = 1;
                                      }
                                      else {      
                                              ccount += 1;
                                      }
                              }
       
                              return max_ccount;  
                      } //}}}
                      function max_delta(days) {  
                              deltas = delta(days);
                              if (deltas.length == 0) return 0;
                              return Math.max.apply(null, deltas);
                      }
                      function min_delta(days) {  
                              deltas = delta(days);
                              if (deltas.length == 0) return 0;
                              return Math.min.apply(null, deltas);
                      }
       
       
                      for (d in total.days) {     
                              total.days[d] = keys(total.days[d]).sort(function(a, b) {return a-b;});
                      }
                      var days2al = {pvdays: 'pv', dldays: 'dl', vpdays: 'vp', sedays: 'se'}; //detail in map function 访问,下载,播放,搜索天数
       
                      var pvdays = total.days.pvdays || [];
                      var dldays = total.days.dldays || [];
                      aldays = {};
                      for (cdi in total.days) {   
                              cd = total.days[cdi];
                              if (!cd) continue;  
                              aldays[days2al[cdi]] = {
                                      d: count(cd),
                                      contd: max_continuous_count(cd),
                                      mindd: min_delta(cd),
                                      maxdd: max_delta(cd),
                              };
                      }
       
                      var min_dl_day = -1;
                      if (dldays.length) {
                              min_dl_day = Math.min(dldays);
                      }
                      dlpvdays = filter(pvdays, function(d) {
                              return d > min_dl_day;
                      });
                      dlpvd = count(dlpvdays);    
       
                      total = extend(total, {dlpvd: dlpvd});
                      total = extend(total, aldays);
       
                      return total;
              } //}}}
       
              var cycle2delta = {
                      week: '7d',
                      month: '1m',
              };
       
              var colname = get_scale_col_name(cycle, firstday);
              var mr_colname = 'mr.' + colname;   
              var ts0 = get_china_day(firstday);  
              var ts1 = date_add(ts0, cycle2delta[cycle]);
              var query = {ts: {$gte: ts0, $lt: ts1}}; // [ts0, ts1)
              db.events.day.mapReduce(
                              m, r, {
                                      verbose: true,
                                      out: mr_colname,
                                      finalize: f,
                                      query: query,
                                      scope: {    
                                              base_ts: ts0,
                                              copy_obj: copy_obj,
                                              filter: filter,
                                              extend: extend,
                                              delta: delta,
                                              keys: keys,
                                      },
                                      jsMode: true,
                              }
                              );
       
              db[mr_colname].find().forEach(function(doc) {
                      var ndoc = extend(doc._id, doc.value);
                      db[colname].insert(ndoc);   
              });
       
      } //}}}

        Attachments

          Activity

            People

            • Votes:
              4 Vote for this issue
              Watchers:
              9 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: