title: how can I release mongodb connections?
body: <p>I have a mongo server with high read/write in a short time. I used python and pymongo, when I wake up this morning I found no connection can make to mongod master cause it's connections reached 19992, its a pretty much scary number</p>
  
  <p>even I stopped all the program, the connection number seems no change</p>
  
  <pre><code>insert  query update delete getmore command flushes mapped  vsize    res faults locked % idx miss %     qr|qw   ar|aw  netIn netOut  conn repl       time
  
  localhost:27417      0      0      0      0       2       1       0   624m  2.87g   287m      0        0          0       0|0     7|0   162b     1k 19992    M   10:36:16
  
  &gt; db.serverStatus(1)
  {
          "host" : "42yl:27417",
          "version" : "1.8.1",
          "process" : "mongod",
          "uptime" : 71732,
          "uptimeEstimate" : 71470,
          "localTime" : ISODate("2011-05-26T03:02:48.301Z"),
          "globalLock" : {
                  "totalTime" : 71732232290,
                  "lockTime" : 149471421,
                  "ratio" : 0.002083741384148133,
                  "currentQueue" : {
                          "total" : 0,
                          "readers" : 0,
                          "writers" : 0
                  },
                  "activeClients" : {
                          "total" : 7,
                          "readers" : 7,
                          "writers" : 0
                  }
          },
          "mem" : {
                  "bits" : 32,
                  "resident" : 258,
                  "virtual" : 910,
                  "supported" : true,
                  "mapped" : 624
          },
          "connections" : {
                  "current" : 19792,
                  "available" : 208
          },
          "extra_info" : {
                  "note" : "fields vary by platform",
                  "heap_usage_bytes" : 562688,
                  "page_faults" : 965
          },
          "indexCounters" : {
                  "btree" : {
                          "accesses" : 12789,
                          "hits" : 12789,
                          "misses" : 0,
                          "resets" : 0,
                          "missRatio" : 0
                  }
          },
          "backgroundFlushing" : {
                  "flushes" : 1195,
                  "total_ms" : 848633,
                  "average_ms" : 710.1531380753138,
                  "last_ms" : 101,
                  "last_finished" : ISODate("2011-05-26T03:02:18.691Z")
          },
          "cursors" : {
                  "totalOpen" : 7,
                  "clientCursors_size" : 7,
                  "timedOut" : 0
          },
          "network" : {
                  "bytesIn" : 685742402,
                  "bytesOut" : 2742190274,
                  "numRequests" : 3800041
          },
          "repl" : {
                  "ismaster" : true
          },
          "opcounters" : {
                  "insert" : 104225,
                  "query" : 9,
                  "update" : 925044,
                  "delete" : 45734,
                  "getmore" : 1642979,
                  "command" : 1119290
          },
          "asserts" : {
                  "regular" : 0,
                  "warning" : 56,
                  "msg" : 0,
                  "user" : 0,
                  "rollovers" : 0
          },
          "writeBacksQueued" : false,
          "ok" : 1
  }
  </code></pre>
  
  <p>I checked the socket connections </p>
  
  <pre><code>Active Internet connections (servers and established) 
  Proto Recv-Q Send-Q Local Address Foreign Address State 
  tcp 0 0 0.0.0.0:60000 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27424 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28417 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28418 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28419 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28420 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28421 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28422 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28423 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:28424 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:38422 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:58422 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:5432 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27417 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27418 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27419 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:8443 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27420 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27421 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27422 0.0.0.0:* LISTEN 
  tcp 0 0 0.0.0.0:27423 0.0.0.0:* LISTEN 
  tcp 0 0 222.73.61.42:27420 222.73.61.43:38249 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56699 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56698 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56697 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56696 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56702 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56701 ESTABLISHED 
  tcp 0 0 127.0.0.1:27417 127.0.0.1:56700 ESTABLISHED 
  tcp 0 0 222.73.61.42:27422 222.73.61.43:33616 ESTABLISHED 
  tcp 0 0 222.73.61.42:27417 222.73.61.43:60218 ESTABLISHED 
  tcp 0 0 222.73.61.42:27423 222.73.61.43:33035 ESTABLISHED 
  tcp 0 3324 222.73.61.42:58422 119.85.195.88:54295 ESTABLISHED 
  tcp 0 0 222.73.61.42:27424 222.73.61.43:55825 ESTABLISHED 
  tcp 0 0 222.73.61.42:54279 222.215.136.8:80 ESTABLISHED 
  tcp 0 0 222.73.61.42:27418 222.73.61.43:37093 ESTABLISHED 
  tcp 0 0 222.73.61.42:27419 222.73.61.43:38346 ESTABLISHED 
  tcp 0 0 127.0.0.1:56702 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56701 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56700 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56699 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56698 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56697 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 127.0.0.1:56696 127.0.0.1:27417 ESTABLISHED 
  tcp 0 0 222.73.61.42:27421 222.73.61.43:39843 ESTABLISHED 
  udp 0 0 0.0.0.0:48514 0.0.0.0:* 
  udp 0 0 222.73.61.42:50721 61.128.128.68:53 ESTABLISHED 
  udp 0 0 127.0.0.1:52274 127.0.0.1:52274 ESTABLISHED 
  Active UNIX domain sockets (servers and established) 
  Proto RefCnt Flags Type State I-Node Path 
  unix 2 [ ACC ] STREAM LISTENING 9081684 /var/run/nscd/socket 
  unix 2 [ ACC ] STREAM LISTENING 18011686 /tmp/mongodb-27417.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011689 /tmp/mongodb-27422.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011691 /tmp/mongodb-28422.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011697 /tmp/mongodb-27420.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011702 /tmp/mongodb-28417.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011693 /tmp/mongodb-27421.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011695 /tmp/mongodb-28421.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011699 /tmp/mongodb-28420.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011710 /tmp/mongodb-27419.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011713 /tmp/mongodb-28419.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011716 /tmp/mongodb-27418.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011719 /tmp/mongodb-28418.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011722 /tmp/mongodb-27424.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011725 /tmp/mongodb-28424.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011728 /tmp/mongodb-27423.sock 
  unix 2 [ ACC ] STREAM LISTENING 18011731 /tmp/mongodb-28423.sock 
  unix 2 [ ACC ] STREAM LISTENING 12771288 /tmp/.s.PGSQL.5432 
  unix 2 [ ] DGRAM 3651 @/org/kernel/udev/udevd 
  unix 5 [ ] DGRAM 16472048 /dev/log 
  unix 2 [ ] STREAM CONNECTED 18706425 /var/run/nscd/socket 
  unix 2 [ ] DGRAM 16792651 
  unix 2 [ ] DGRAM 16472057 
  unix 2 [ ] DGRAM 16472052 
  </code></pre>