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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
2.6 KiB
2.6 KiB
来自 C++那些事网站 的文章，由站点同步脚本导出。
C++ 内存泄漏排查实战
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;
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7cfdd48 in block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7cfdd48 in block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7cfc580 (seg1 slice1 127.0.1.1:7003 pid=4295)
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x87f85c8 in block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7d3c5c8 in block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x87f85c8 in block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
WARNING: problem in alloc set ExecutorState: bad single-chunk 0x7d3c5c8 in block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x87f6e00 (seg0 slice1 127.0.1.1:7002 pid=4294)
WARNING: problem in alloc set ExecutorState: found inconsistent memory block 0x7d3ae00 (seg2 slice1 127.0.1.1:7004 pid=4296)
调试：
(gdb) b aset.c:1109 if chunk=0x7cfdd48
Breakpoint 1 at 0x105d420: file aset.c, line 1109.
(gdb) c
Continuing.
Thread 1 "postgres" hit Breakpoint 1, AllocSetAlloc (context=0x787ac50, size=4096) at aset.c:1109
1109 block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
(gdb) p chunk
$1 = (AllocChunk) 0x7cfdd48
(gdb) p chunk->size
$2 = 9187201950435737471
(gdb) p &chunk->size
$3 = (Size *) 0x7cfdd48
(gdb) watch (*((Size *) 0x7cfdd48))
Hardware watchpoint 2: (*((Size *) 0x7cfdd48))
(gdb) i b
Num Type Disp Enb Address What
1 breakpoint keep y 0x000000000105d420 in AllocSetAlloc at aset.c:1109
stop only if chunk=0x7cfdd48
breakpoint already hit 1 time
2 hw watchpoint keep y (*((Size *) 0x7cfdd48))
(gdb) d 1
(gdb) c