title: why did my app just used about 36MB memory but i still receive low memory warning?
body: <p>i use instruments to track my app's usage of memory,in memory monitor,i find that real memory is below 36MB ,and most time it just 32MB,but i still get warnings low memory in organizer and crashed.</p>
  
  <pre><code>Incident Identifier: CFEF044E-E839-4DB7-9ED6-E22CD92B9171
  CrashReporter Key:   80954447762f1882da7df309d5493cf8647f4c8b
  OS Version:          iPhone OS 3.2 (7B367)
  Date:                2010-08-10 15:21:25 +0800
  
  Free pages:        593
  Wired pages:       18705
  Purgeable pages:   1664
  Largest process:   iPad4HB
  
  Processes
           Name                 UUID                    Count resident pages
           iPad4HB &lt;51ec4f748adb8d99e4456ba49644e516&gt;   27182 (jettisoned) (active)
       debugserver &lt;6f10136b8d55ad8cbd29c09a402b1f94&gt;     149
      syslog_relay &lt;4ceaed776d2df957fa130712f4ef21d0&gt;      70
  notification_pro &lt;4c9a7ee0a5bbe160465991228f2d2f2e&gt;      71
               lsd &lt;a4d852c1c8da2b3d231bdc90887b52ba&gt;     143
              apsd &lt;f655e615956fa9881fd423d762791e7d&gt;     197
           notifyd &lt;5e9d5bee7c3eae1c8b494c79eb11406e&gt;      62
          BTServer &lt;64e4a6ea6b1240db2331e05a29caa862&gt;     132
        CommCenter &lt;97bf297944ac4bde19bcee96dd23bd5f&gt;     191
       SpringBoard &lt;c7a5904c12db7b14334a4edaa4cabaa9&gt;    4844 (active)
        accessoryd &lt;b4e1403f53e4c7b53b0ec833007f6589&gt;     122
           configd &lt;aca9fa3380322669164fd6b1a3864300&gt;     374
     fairplayd.K48 &lt;2d997ffca1a568f9c5400ac32d8f0782&gt;      86
         locationd &lt;dd1ea88105c62173908ce767db5c4d37&gt;     654
     mDNSResponder &lt;820560222d47a1f2a0dce98a7f8a9721&gt;     112
      mediaserverd &lt;ea8bac28b06fe3980fdd44b5caceb563&gt;    5931
         lockdownd &lt;497fd54c79a680bf29f5d9320f514613&gt;     579
  MobileStorageMou &lt;c277b79c2157c4dc5cfc5c3ca35bd5f2&gt;      76
           syslogd &lt;66247e305d5c0bf6f1ce1cc950653263&gt;      80
              ptpd &lt;83de0f774bd6553d513ae9e19b0f9b56&gt;     233
           launchd &lt;66972eee4d865c4383b33d985d22994b&gt;      72
  
  **End**
  Tue Aug 10 15:12:05 hokudaiaoniaowangruande-iPad SpringBoard[26] &lt;Warning&gt;: Received memory warning. Level=1
  Tue Aug 10 15:12:05 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: Received memory warning. Level=1
  Tue Aug 10 15:12:20 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:12:32 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:12:32 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:12:37 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:13:28 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:13:28 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:13:44 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:14:11 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:14:11 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:14:20 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:14:50 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:14:50 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:14:56 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:15:02 hokudaiaoniaowangruande-iPad mDNSResponder[19] &lt;Error&gt;: ERROR: mDNSPlatformReadTCP - recv: 60 (Operation timed out)
  Tue Aug 10 15:16:11 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:16:11 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:17:33 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:17:44 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:17:44 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:18:01 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad configd[24] &lt;Notice&gt;: jetsam: kernel memory event (90), free: 695, active: 1734, inactive: 985, purgeable: 3456, wired: 18656
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad SpringBoard[26] &lt;Warning&gt;: Received memory warning. Level=2
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: Received memory warning. Level=2
  Tue Aug 10 15:18:07 hokudaiaoniaowangruande-iPad SpringBoard[26] &lt;Warning&gt;: Memory level is urgent (10%) and there are no background apps to ask to exit.
  Tue Aug 10 15:19:07 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:19:15 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:19:15 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:20:02 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:20:06 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:20:06 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:21:01 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:21:06 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playable
  Tue Aug 10 15:21:06 hokudaiaoniaowangruande-iPad iPad4HB[107] &lt;Warning&gt;: playing
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad configd[24] &lt;Notice&gt;: jetsam: kernel termination snapshot being created
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad com.apple.launchd[1] (UIKitApplication:com.yourcompany.iPad4HB[0x4df4][107]) &lt;Notice&gt;: (UIKitApplication:com.yourcompany.iPad4HB[0x4df4]) Bug: launchd_core_logic.c:3232 (24063):0
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad com.apple.launchd[1] (UIKitApplication:com.yourcompany.iPad4HB[0x4df4][107]) &lt;Notice&gt;: (UIKitApplication:com.yourcompany.iPad4HB[0x4df4]) Bug: launchd_core_logic.c:3309 (24063):0
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad com.apple.debugserver-44[106] &lt;Warning&gt;: 1 [006a/1703]: error: ::read ( 6, 0x2809f4, 1024 ) =&gt; -1 err = Bad file descriptor (0x00000009)
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad com.apple.launchd[1] (UIKitApplication:com.yourcompany.iPad4HB[0x4df4][107]) &lt;Notice&gt;: (UIKitApplication:com.yourcompany.iPad4HB[0x4df4]) Bug: launchd_core_logic.c:2650 (24063):10
  Tue Aug 10 15:21:24 hokudaiaoniaowangruande-iPad com.apple.launchd[1] (UIKitApplication:com.yourcompany.iPad4HB[0x4df4][107]) &lt;Notice&gt;: (UIKitApplication:com.yourcompany.iPad4HB[0x4df4]) Working around 5020256. Assuming the job crashed.
  </code></pre>