A method of locating memory leaks (Linux) __linux

This article is the Linux version of a method for locating memory leaks (Solaris), which uses GDB. Mainly introduces the example part. See "A method of locating memory leaks (Solaris)." Example:

To simulate a new failed program:

#include <stdexcept>

Class ABC

{

Public

Virtual ~abc () {}

int i;

Int J;

};

void F ()

{

for (int i = 0; i < 1000; ++i)

{

abc* p = new ABC;

}

Throw Std::bad_alloc ();

}

int main ()

{

f ();

return 0;

}

1 compile and run this piece of code. Generate a core file

2 Open this core file with GDB:

GDB A.out Core

(GDB) Run

Starting program:/test/new_fail/a.out

Terminate called after throwing a instance of ' Std::bad_alloc '

What (): Std::bad_alloc

Program received signal SIGABRT, aborted.

0x00007ffff733f645 in Raise () from/lib64/libc.so.6

(GDB) Info proc

Process 10683

CmdLine = '/test/new_fail/a.out '

CWD = '/test/new_fail '

EXE = '/test/new_fail/a.out '

(gdb) Shell Pmap 10683

10683:a.out

START SIZE RSS PSS DIRTY SWAP PERM MAPPING

0000000000400000 4K 4K 4K 0K 0K r-xp/test/new_fail/a.out

0000000000600000 4K 4K 4K 4K 0K r--p/test/new_fail/a.out

0000000000601000 4K 4K 4K 4K 0K rw-p/test/new_fail/a.out

0000000000602000 132K 32K 32K 32K 0K rw-p [Heap]

... Slightly

total:11468k 1048K 684K 180K 0K

360K writable-private, 11108K readonly-private, 0K shared, and 1048K referenced

You can see that the starting address of the heap space is 0x0000000000602000, a total of 132K bytes, that is, 132*1024=135168 bytes.

3 because it is a 64-bit application, the pointer occupies 8 bytes. So the number of pointers that need to be traversed is 135168/8=16896.

4 Output The results to the log file Gdb.txt:

(gdb) Set height 0

(GDB) Set logging on

Copying output to Gdb.txt.

(GDB) x/16896a 0x0000000000602000

Content of Gdb.txt:

0x602000:0x0 0x21

0x602010:0x400b30 <_ZTV3ABC+16> 0x0

0x602020:0x0 0x21

0x602030:0x400b30 <_ZTV3ABC+16> 0x0

....

5) Filtration Gdb.txt:

awk ' {print $ '/n ' $} ' gdb.txt|c++filt|grep Vtable>gdb_vtable.txt

The contents of the Gdb_vtable.txt are:

<vtable for Abc+16>

<vtable for Abc+16>

<vtable for Abc+16>

<vtable for Abc+16>

....

6 Import gdb_vtable.txt content into SQL Server (if you don't have a lot of records, you can replace it with Excel). The table name is Gdb_vtable, and the first column Col001 is a symbol. Sum it up by grouping:

Select Col001, COUNT (1) Quantity from gdb_vtable

GROUP BY Col001

ORDER BY Quantity desc

The results are:

Col001 Quantity

<vtable for Abc+16> 1000

<vtable for std::bad_alloc@ @GLIBCXX_3 .4+16> 1

There are 1000 ABC in the core, traversing the code using ABC to know that there is a leak.