mirror of
https://github.com/Light-City/CPlusPlusThings.git
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dfe1c933b3
- const README: rewrite the space-saving claim per issue #5 follow-ups (constant-expression const vs #define immediates; which const qualify as constant expressions) - const README: fix the class-section diagnosis per issue #338 (overload resolution picks the const overload; the restriction only surfaces once that overload is removed) - sizeof README: virtual-inheritance result is compiler-dependent (GCC merges vbptr+vfptr -> 16, MSVC keeps them separate -> 32) #246 - static README: new section on internal linkage / access restriction with anonymous-namespace comparison #142 - 10-day practice: full problem list table + fixed day links #136 - new design_pattern/singleton/singleton_default.hpp: reusable thread-safe CRTP singleton template, compile+concurrency tested #303
50 lines
2.6 KiB
Markdown
50 lines
2.6 KiB
Markdown
> 来自 [C++那些事网站](https://light-city.github.io/stories_things/cpp-tools/memory-leak-debug-session/) 的文章，由站点同步脚本导出。
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# C++ 内存泄漏排查实战
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```
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regression=# SELECT t1.a, t1.c, t2.b, t2.c FROM prt1_e t1, prt2_e t2 WHERE (t1.a + t1.b)/2 = (t2.b + t2.a)/2 AND t1.c = 0 ORDER BY t1.a, t2.b;
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7cfdd48 in block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7cfdd48 in block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x87f85c8 in block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7d3c5c8 in block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x87f85c8 in block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
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WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7d3c5c8 in block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
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WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
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```
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调试：
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```
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(gdb) b aset.c:1109 if chunk=0x7cfdd48
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Breakpoint 1 at 0x105d420: file aset.c, line 1109.
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(gdb) c
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Continuing.
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Thread 1 "postgres" hit Breakpoint 1, AllocSetAlloc (context=0x787ac50, size=4096) at aset.c:1109
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1109 block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
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(gdb) p chunk
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$1 = (AllocChunk) 0x7cfdd48
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(gdb) p chunk->size
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$2 = 9187201950435737471
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(gdb) p &chunk->size
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$3 = (Size *) 0x7cfdd48
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(gdb) watch (*((Size *) 0x7cfdd48))
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Hardware watchpoint 2: (*((Size *) 0x7cfdd48))
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(gdb) i b
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Num Type Disp Enb Address What
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1 breakpoint keep y 0x000000000105d420 in AllocSetAlloc at aset.c:1109
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stop only if chunk=0x7cfdd48
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breakpoint already hit 1 time
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2 hw watchpoint keep y (*((Size *) 0x7cfdd48))
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(gdb) d 1
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(gdb) c
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``` |