我在处理 bad_alloc 时遇到问题。当它尝试重新定位和分配 2Mb 时，它会在 std::vector.push_back 期间抛出
堆状态是
Heap Flags Reserv Commit Virt Free List UCR Virt Lock Fast
(k) (k) (k) (k) length blocks cont. heap
-----------------------------------------------------------------------------
04e00000 00000002 67704 41088 67704 40735 135 135 0 25 LFH
External fragmentation 99 % (135 free blocks)
Virtual address fragmentation 39 % (135 uncommited ranges)
...
0c8f0000 00001002 82216 81384 82216 8247 172196 13 5 3 LFH
...
0: Heap 04e00000
Flags 00000002 - HEAP_GROWABLE
Reserved memory in segments 67704 (k)
Commited memory in segments 41088 (k)
Virtual bytes (correction for large UCR) 58644 (k)
Free space 40735 (k) (135 blocks)
External fragmentation 99% (135 free blocks)
Virtual address fragmentation 29% (135 uncommited ranges)
Virtual blocks 0 - total 0 KBytes
Lock contention 37
Segments 1
Low fragmentation heap 04e044f0
Lock contention 0
Metadata usage 0 bytes
Statistics:
Segments created 0
Segments deleted 0
Segments reused 0
Block cache:
Buckets info:
Size Blocks Seg Empty Aff Distribution
------------------------------------------------
------------------------------------------------
Default heap Front heap Unused bytes
Range (bytes) Busy Free Busy Free Total Average
------------------------------------------------------------------
0 - 1024 217 0 0 0 487 2
1024 - 2048 1 0 0 0 1 1
3072 - 4096 0 1 0 0 0 0
15360 - 16384 1 0 0 0 1 1
203776 - 204800 0 2 0 0 0 0
220160 - 221184 0 2 0 0 0 0
224256 - 225280 0 1 0 0 0 0
236544 - 237568 0 2 0 0 0 0
240640 - 241664 0 1 0 0 0 0
257024 - 258048 0 1 0 0 0 0
265216 - 266240 0 4 0 0 0 0
273408 - 274432 0 1 0 0 0 0
277504 - 278528 0 2 0 0 0 0
281600 - 282624 0 2 0 0 0 0
285696 - 286720 0 6 0 0 0 0
289792 - 290816 0 4 0 0 0 0
293888 - 294912 0 12 0 0 0 0
297984 - 299008 0 10 0 0 0 0
302080 - 303104 0 13 0 0 0 0
306176 - 307200 0 14 0 0 0 0
310272 - 311296 0 19 0 0 0 0
314368 - 315392 0 15 0 0 0 0
318464 - 319488 0 3 0 0 0 0
326656 - 327680 0 1 0 0 0 0
330752 - 331776 0 3 0 0 0 0
333824 - 334848 1 0 0 0 8 8
351232 - 352256 0 1 0 0 0 0
363520 - 364544 0 2 0 0 0 0
367616 - 368640 0 1 0 0 0 0
396288 - 397312 0 3 0 0 0 0
416768 - 417792 0 1 0 0 0 0
420864 - 421888 0 2 0 0 0 0
424960 - 425984 0 1 0 0 0 0
433152 - 434176 0 1 0 0 0 0
437248 - 438272 0 1 0 0 0 0
466944 - 467968 0 1 0 0 0 0
470016 - 471040 0 1 0 0 0 0
482304 - 483328 0 1 0 0 0 0
------------------------------------------------------------------
Total 220 135 0 0 497 2
0: Heap 0c8f0000
Flags 00001002 - HEAP_GROWABLE
Reserved memory in segments 82216 (k)
Commited memory in segments 81384 (k)
Virtual bytes (correction for large UCR) 81620 (k)
Free space 8247 (k) (172196 blocks)
External fragmentation 10% (172196 free blocks)
Virtual address fragmentation 0% (13 uncommited ranges)
Virtual blocks 5 - total 0 KBytes
Lock contention 3
Segments 1
Low fragmentation heap 43230048
Lock contention 0
Metadata usage 4096 bytes
Statistics:
Segments created 120
Segments deleted 2
Segments reused 0
Block cache:
5: 4096 bytes ( 54, 0)
6: 8192 bytes ( 26, 0)
7: 16384 bytes ( 13, 0)
8: 32768 bytes ( 8, 0)
9: 65536 bytes ( 9, 0)
10: 131072 bytes ( 5, 0)
11: 262144 bytes ( 4, 1)
Buckets info:
Size Blocks Seg Empty Aff Distribution
------------------------------------------------
64 25483 53 0 0 (53-25483)
72 2991 30 0 0 (30-2991)
80 750 15 0 0 (15-750)
88 46 1 1 0 (1-46)
96 42 1 1 0 (1-42)
104 39 1 1 0 (1-39)
112 36 1 1 0 (1-36)
120 33 1 1 0 (1-33)
128 63 1 1 0 (1-63)
136 60 1 1 0 (1-60)
144 56 1 1 0 (1-56)
152 53 1 1 0 (1-53)
160 51 1 1 0 (1-51)
168 48 1 1 0 (1-48)
200 40 1 1 0 (1-40)
208 39 1 1 0 (1-39)
224 36 1 1 0 (1-36)
280 29 1 1 0 (1-29)
312 26 1 1 0 (1-26)
7432 17 1 1 0 (1-17)
9736 26 1 1 0 (1-26)
10760 24 1 1 0 (1-24)
11784 22 1 1 0 (1-22)
------------------------------------------------
Default heap Front heap Unused bytes
Range (bytes) Busy Free Busy Free Total Average
------------------------------------------------------------------
0 - 1024 619437 172194 28854 1067 11637848 17
1024 - 2048 10 1 0 0 113 11
3072 - 4096 2 0 0 0 32 16
4096 - 5120 1 0 0 0 16 16
5120 - 6144 1 0 0 0 20 20
7168 - 8192 1 0 0 17 20 20
9216 - 10240 0 0 0 26 0 0
10240 - 11264 0 0 0 24 0 0
11264 - 12288 0 0 0 22 0 0
12288 - 13312 2 0 0 0 32 16
15360 - 16384 1 0 0 0 1 1
16384 - 17408 2 0 0 0 32 16
20480 - 21504 1 0 0 0 8 8
21504 - 22528 1 0 0 0 20 20
40960 - 41984 1 0 0 0 8 8
43008 - 44032 1 0 0 0 16 16
48128 - 49152 1 0 0 0 16 16
54272 - 55296 1 0 0 0 8 8
58368 - 59392 1 0 0 0 17 17
72704 - 73728 1 0 0 0 20 20
83968 - 84992 0 1 0 0 0 0
96256 - 97280 1 0 0 0 16 16
108544 - 109568 1 0 0 0 16 16
116736 - 117760 1 0 0 0 21 21
139264 - 140288 1 0 0 0 16 16
145408 - 146432 1 0 0 0 16 16
159744 - 160768 1 0 0 0 22 22
163840 - 164864 1 0 0 0 20 20
193536 - 194560 1 0 0 0 20 20
262144 - 263168 3 0 0 0 40 13
327680 - 328704 1 0 0 0 16 16
333824 - 334848 1 0 0 0 8 8
436224 - 437248 1 0 0 0 16 16
------------------------------------------------------------------
Total 619479 172196 28854 1156 11638454 17
我的问题是外部碎片 99% 是什么意思，为什么是“堆碎片”而不是“虚拟地址空间碎片”？
“外部碎片”(99%)和“虚拟地址碎片”(29%)有什么区别？
创建一个新堆，可能有帮助吗？
PS:我在同一个过程中有很多托管代码。私有(private)工作集是 1.8Gb。
最佳答案
基本上你有大量非常小的对象分配，这会导致碎片。此外，您在同一个进程中混合了 native 和托管代码，并且正在分配大量内存。这些方法需要内存管理。最好在进程启动时为大内存分配创建一个专用堆以避免此类问题。堆应该只用于 native 代码的大内存分配。
此外，最好分析一下托管代码为何需要这么多内存。
关于c++ - WinDbg 的外部碎片是什么意思？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/8316764/