16GB内存系统中占用1.3GB的.NET应用抛出OutOfMemoryException排查

基础信息 #

• 应用：Windows 10 64位.NET WinForms应用，以AnyCPU编译并关闭Prefer 32-bit选项，包含目标为x64的CLI/C++项目，无法在32位环境运行
• 系统：16GB内存
• 转储文件：大小1.3GB，经dotMemory分析，托管堆已分配220MB，其中108MB被占用；应用在其他场景下可正常占用超过1.3GB内存

异常堆栈 #

System.OutOfMemoryException: Out of memory.
at System.Drawing.Graphics.FromHdcInternal(IntPtr hdc)
at System.Drawing.Graphics.FromHdc(IntPtr hdc)
at DevExpress.XtraBars.Docking2010.DocumentsHost.DoPaint(Message& m)
at DevExpress.XtraBars.Docking2010.DocumentsHost.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

已完成的排查 #

• 托管堆碎片：dotMemory的托管内存报告未发现异常
• 内存区域状态：WinDbg执行!address -summary显示，进程内存大部分为保留（reserve）状态，提交（commit）仅1.25GB，具体输出如下：

  0:000> !address -summary
  --- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
  Free                                    405     7ffe`8db96000 ( 127.994 TB)          100.00%
  <unknown>                              1515        1`3f3b3000 (   4.988 GB)  86.22%    0.00%
  Image                                  2261        0`25f26000 ( 607.148 MB)  10.25%    0.00%
  Heap                                    120        0`08324000 ( 131.141 MB)   2.21%    0.00%
  Stack                                   234        0`04bc0000 (  75.750 MB)   1.28%    0.00%
  Other                                    39        0`00200000 (   2.000 MB)   0.03%    0.00%
  TEB                                      78        0`0009c000 ( 624.000 kB)   0.01%    0.00%
  PEB                                       1        0`00001000 (   4.000 kB)   0.00%    0.00%
  
  --- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotal
  MEM_PRIVATE                            1882        1`452fe000 (   5.081 GB)  87.82%    0.00%
  MEM_IMAGE                              2261        0`25f26000 ( 607.148 MB)  10.25%    0.00%
  MEM_MAPPED                              105        0`07236000 ( 114.211 MB)   1.93%    0.00%
  
  --- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
  MEM_FREE                                405     7ffe`8db96000 ( 127.994 TB)          100.00%
  MEM_RESERVE                             681        1`22426000 (   4.535 GB)  78.39%    0.00%
  MEM_COMMIT                             3567        0`50034000 (   1.250 GB)  21.61%    0.00%
  
  --- Protect Summary (for commit) - RgnCount ----------- Total Size -------- %ofBusy %ofTotal
  PAGE_READWRITE                         1835        0`23d12000 ( 573.070 MB)   9.67%    0.00%
  PAGE_EXECUTE_READ                       195        0`15090000 ( 336.563 MB)   5.68%    0.00%
  PAGE_READONLY                           854        0`13fde000 ( 319.867 MB)   5.40%    0.00%
  PAGE_WRITECOPY                          484        0`01633000 (  22.199 MB)   0.37%    0.00%
  PAGE_EXECUTE_READWRITE                   92        0`012db000 (  18.855 MB)   0.32%    0.00%
  PAGE_READWRITE|PAGE_WRITECOMBINE          5        0`00830000 (   8.188 MB)   0.14%    0.00%
  PAGE_READWRITE|PAGE_GUARD                78        0`0015e000 (   1.367 MB)   0.02%    0.00%
  PAGE_NOACCESS                            24        0`00018000 (  96.000 kB)   0.00%    0.00%
  
  --- Largest Region by Usage ----------- Base Address -------- Region Size ----------
  Free                                    213`79810000     7de1`2f130000 ( 125.880 TB)
  <unknown>                              7ff4`a8af0000        1`00020000 (   4.000 GB)
  Image                                  7ffd`06181000        0`03b43000 (  59.262 MB)
  Heap                                    213`6b332000        0`0095d000 (   9.363 MB)
  Stack                                    52`c8600000        0`000fb000 (1004.000 kB)
  Other                                   213`311e0000        0`00181000 (   1.504 MB)
  TEB                                      52`c8000000        0`00002000 (   8.000 kB)
  PEB                                      52`c8158000        0`00001000 (   4.000 kB)
  

• GDI/用户句柄：已设置监控，当句柄数达到8000时触发告警，远低于系统10000的上限，未触发告警
• Bitmap资源：对比正常与异常场景，Bitmap实例数量均约为1000个，未发现大量未释放的大Bitmap

疑问 #

目前无法解释为何16GB内存系统中，仅占用1.3GB内存的应用会抛出System.OutOfMemoryException，还有哪些可能的原因？是否为非托管内存碎片？该如何进一步排查？

内容的提问来源于stack exchange，提问作者Stijn