title: RethinkDB: why does rethinkdb service use so much memory?
body: <p>After encountering situations where I found that rethinkdb service is down for unknown reason, I noticed it uses a lot of memory:</p>
  
  <pre><code># free -m
                    total       used       free     shared    buffers     cached
      Mem:          7872       7744        128          0         30         68
      -/+ buffers/cache:       7645        226
      Swap:         4031        287       3744
  
  # top
  top - 23:12:51 up 7 days,  1:16,  3 users,  load average: 0.00, 0.00, 0.00
  Tasks: 133 total,   1 running, 132 sleeping,   0 stopped,   0 zombie
  Cpu(s):  0.0%us,  0.2%sy,  0.0%ni, 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
  Mem:   8061372k total,  7931724k used,   129648k free,    32752k buffers
  Swap:  4128760k total,   294732k used,  3834028k free,    71260k cached
  
    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                           
   1835 root      20   0 7830m 7.2g 5480 S  1.0 94.1 292:43.38 rethinkdb                                                         
  29417 root      20   0 15036 1256  944 R  0.3  0.0   0:00.05 top                                                               
      1 root      20   0 19364 1016  872 S  0.0  0.0   0:00.87 init
  
  
  
  # cat log_file  | tail -9
  2014-09-22T21:56:47.448701122 0.052935s info: Running rethinkdb 1.12.5 (GCC 4.4.7)...
  2014-09-22T21:56:47.452809839 0.057044s info: Running on Linux 2.6.32-431.17.1.el6.x86_64 x86_64
  2014-09-22T21:56:47.452969820 0.057204s info: Using cache size of 3327 MB
  2014-09-22T21:56:47.453169285 0.057404s info: Loading data from directory /rethinkdb_data
  2014-09-22T21:56:47.571843375 0.176078s info: Listening for intracluster connections on port 29015
  2014-09-22T21:56:47.587691636 0.191926s info: Listening for client driver connections on port 28015
  2014-09-22T21:56:47.587912507 0.192147s info: Listening for administrative HTTP connections on port 8080
  2014-09-22T21:56:47.595163724 0.199398s info: Listening on addresses
  2014-09-22T21:56:47.595167377 0.199401s info: Server ready
  </code></pre>
  
  <p>It seems a lot considering the size of the files:</p>
  
  <pre><code># du -h
  4.0K    ./tmp
  156M    .
  </code></pre>
  
  <p>Do I need to configure a different cache size? Do you think it has something to do with finding the service surprisingly gone? I'm using v1.12.5</p>