Punctuated Memory Leak
An example of this pattern is somewhat similar to a large block allocation leak for process heap (please see a modeling example in Volume 5, page 315). An application has some functionality and after each command its committed memory was increasing by 50 - 60 Mb. 3 process memory dumps were taken with one before failures and then after each failure:
// Before failures
0:000> !address -summary --- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal Free 267 76c50000 ( 1.856 Gb) 92.79% <unclassified> 270 4d6f000 ( 77.434 Mb) 52.45% 3.78% Image 620 31bf000 ( 49.746 Mb) 33.70% 2.43% Stack 60 1400000 ( 20.000 Mb) 13.55% 0.98% ActivationContextData 48 35000 ( 212.000 kb) 0.14% 0.01% NlsTables 1 23000 ( 140.000 kb) 0.09% 0.01% TEB 20 14000 ( 80.000 kb) 0.05% 0.00% CsrSharedMemory 1 5000 ( 20.000 kb) 0.01% 0.00% PEB 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotal MEM_PRIVATE 296 3bca000 ( 59.789 Mb) 40.50% 2.92% MEM_IMAGE 647 340c000 ( 52.047 Mb) 35.26% 2.54% MEM_MAPPED 78 23ca000 ( 35.789 Mb) 24.24% 1.75%
--- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal MEM_FREE 267 76c50000 ( 1.856 Gb) 92.79% MEM_RESERVE 125 5006000 ( 80.023 Mb) 54.21% 3.91% MEM_COMMIT 896 439a000 ( 67.602 Mb) 45.79% 3.30%
--- Protect Summary (for commit) - RgnCount ----------- Total Size -------- %ofBusy %ofTotal PAGE_EXECUTE_READ 125 1f2c000 ( 31.172 Mb) 21.12% 1.52% PAGE_READONLY 363 1ee5000 ( 30.895 Mb) 20.93% 1.51% PAGE_READWRITE 309 4c2000 ( 4.758 Mb) 3.22% 0.23% PAGE_WRITECOPY 43 6a000 ( 424.000 kb) 0.28% 0.02% PAGE_READWRITE|PAGE_GUARD 40 4b000 ( 300.000 kb) 0.20% 0.01% PAGE_EXECUTE_READWRITE 15 11000 ( 68.000 kb) 0.04% 0.00% PAGE_EXECUTE 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Largest Region by Usage ----------- Base Address -------- Region Size ---------- Free 6130000 5fb70000 ( 1.496 Gb) <unclassified> abf000 13d1000 ( 19.816 Mb) Image 75141000 879000 ( 8.473 Mb) Stack 3290000 fd000 (1012.000 kb) ActivationContextData 50000 4000 ( 16.000 kb) NlsTables 7efb0000 23000 ( 140.000 kb) TEB 7ef6f000 1000 ( 4.000 kb) CsrSharedMemory 7efe0000 5000 ( 20.000 kb) PEB 7efde000 1000 ( 4.000 kb)
// After the 1st failure
0:000> !address -summary
--- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
Free 267 7388c000 ( 1.805 Gb) 90.26%
<unclassified> 272 8133000 ( 129.199 Mb) 64.80% 6.31%
Image 614 31bf000 ( 49.746 Mb) 24.95% 2.43%
Stack 60 1400000 ( 20.000 Mb) 10.03% 0.98%
ActivationContextData 48 35000 ( 212.000 kb) 0.10% 0.01%
NlsTables 1 23000 ( 140.000 kb) 0.07% 0.01%
TEB 20 14000 ( 80.000 kb) 0.04% 0.00%
CsrSharedMemory 1 5000 ( 20.000 kb) 0.01% 0.00%
PEB 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_PRIVATE 297 6f8e000 ( 111.555 Mb) 55.95% 5.45%
MEM_IMAGE 642 340c000 ( 52.047 Mb) 26.10% 2.54%
MEM_MAPPED 78 23ca000 ( 35.789 Mb) 17.95% 1.75%
--- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_FREE 267 7388c000 ( 1.805 Gb) 90.26%
MEM_COMMIT 892 775e000 ( 119.367 Mb) 59.87% 5.83%
MEM_RESERVE 125 5006000 ( 80.023 Mb) 40.13% 3.91%
--- Protect Summary (for commit) - RgnCount ----------- Total Size -------- %ofBusy %ofTotal
PAGE_READWRITE 314 38a3000 ( 56.637 Mb) 28.40% 2.77%
PAGE_EXECUTE_READ 125 1f2c000 ( 31.172 Mb) 15.63% 1.52%
PAGE_READONLY 363 1ee5000 ( 30.895 Mb) 15.49% 1.51%
PAGE_WRITECOPY 34 4d000 ( 308.000 kb) 0.15% 0.01%
PAGE_READWRITE|PAGE_GUARD 40 4b000 ( 300.000 kb) 0.15% 0.01%
PAGE_EXECUTE_READWRITE 15 11000 ( 68.000 kb) 0.03% 0.00%
PAGE_EXECUTE 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Largest Region by Usage ----------- Base Address -------- Region Size ----------
Free 94f4000 5c7ac000 ( 1.445 Gb)
<unclassified> 6130000 33c4000 ( 51.766 Mb)
Image 75141000 879000 ( 8.473 Mb)
Stack 3290000 fd000 (1012.000 kb)
ActivationContextData 50000 4000 ( 16.000 kb)
NlsTables 7efb0000 23000 ( 140.000 kb)
TEB 7ef6f000 1000 ( 4.000 kb)
CsrSharedMemory 7efe0000 5000 ( 20.000 kb)
PEB 7efde000 1000 ( 4.000 kb)
0:000> !address -f:VAR
BaseAddr EndAddr+1 RgnSize Type State Protect Usage
-------------------------------------------------------------------------------------------
[...]
5e82000 5f70000 ee000 MEM_PRIVATE MEM_RESERVE <unclassified>
6130000 94f4000 33c4000 MEM_PRIVATE MEM_COMMIT PAGE_READWRITE <unclassified>
74220000 74221000 1000 MEM_IMAGE MEM_COMMIT PAGE_READONLY <unclassified>
[...]
0:000> ? 33c4000/0n1024
Evaluate expression: 53008 = 0000cf10
// After the 2nd failure
0:000> !address -summary
--- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
Free 268 704c8000 ( 1.755 Gb) 87.74%
<unclassified> 273 b4f7000 ( 180.965 Mb) 72.05% 8.84%
Image 614 31bf000 ( 49.746 Mb) 19.81% 2.43%
Stack 60 1400000 ( 20.000 Mb) 7.96% 0.98%
ActivationContextData 48 35000 ( 212.000 kb) 0.08% 0.01%
NlsTables 1 23000 ( 140.000 kb) 0.05% 0.01%
TEB 20 14000 ( 80.000 kb) 0.03% 0.00%
CsrSharedMemory 1 5000 ( 20.000 kb) 0.01% 0.00%
PEB 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_PRIVATE 298 a352000 ( 163.320 Mb) 65.03% 7.97%
MEM_IMAGE 642 340c000 ( 52.047 Mb) 20.72% 2.54%
MEM_MAPPED 78 23ca000 ( 35.789 Mb) 14.25% 1.75%
--- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_FREE 268 704c8000 ( 1.755 Gb) 87.74%
MEM_COMMIT 893 ab22000 ( 171.133 Mb) 68.14% 8.36%
MEM_RESERVE 125 5006000 ( 80.023 Mb) 31.86% 3.91%
--- Protect Summary (for commit) - RgnCount ----------- Total Size -------- %ofBusy %ofTotal
PAGE_READWRITE 315 6c67000 ( 108.402 Mb) 43.16% 5.29%
PAGE_EXECUTE_READ 125 1f2c000 ( 31.172 Mb) 12.41% 1.52%
PAGE_READONLY 363 1ee5000 ( 30.895 Mb) 12.30% 1.51%
PAGE_WRITECOPY 34 4d000 ( 308.000 kb) 0.12% 0.01%
PAGE_READWRITE|PAGE_GUARD 40 4b000 ( 300.000 kb) 0.12% 0.01%
PAGE_EXECUTE_READWRITE 15 11000 ( 68.000 kb) 0.03% 0.00%
PAGE_EXECUTE 1 1000 ( 4.000 kb) 0.00% 0.00%
--- Largest Region by Usage ----------- Base Address -------- Region Size ----------
Free c8c4000 593dc000 ( 1.394 Gb)
<unclassified> 6130000 33c4000 ( 51.766 Mb)
Image 75141000 879000 ( 8.473 Mb)
Stack 3290000 fd000 (1012.000 kb)
ActivationContextData 50000 4000 ( 16.000 kb)
NlsTables 7efb0000 23000 ( 140.000 kb)
TEB 7ef6f000 1000 ( 4.000 kb)
CsrSharedMemory 7efe0000 5000 ( 20.000 kb)
PEB 7efde000 1000 ( 4.000 kb)
0:000> !address -f:VAR
BaseAddr EndAddr+1 RgnSize Type State Protect Usage ------------------------------------------------------------------------------------------- 5e82000 5f70000 ee000 MEM_PRIVATE MEM_RESERVE <unclassified> 6130000 94f4000 33c4000 MEM_PRIVATE MEM_COMMIT PAGE_READWRITE <unclassified> 9500000 c8c4000 33c4000 MEM_PRIVATE MEM_COMMIT PAGE_READWRITE <unclassified> 74220000 74221000 1000 MEM_IMAGE MEM_COMMIT PAGE_READONLY <unclassified> [...]
The name of this pattern comes from the process of discrete large memory allocations that happen after specific actions or events. Between them there are no visible or substantial increases in memory usage.
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