Valgrind is a memory debugging tool for Linux (x86, x86_64, and PPC32) programs that can monitor memory usage of the compiled binaries (malloc and free in C, and new and delete in the C + +). Identify memory leak issues.
The Memcheck tool included in Valgrind can check for the following program errors:
Using uninitialized memory (use of uninitialised memories)
Use memory that has been freed (reading/writing memories after it have been free ' d)
Use over malloc allocated memory space (reading/writing off the end of malloc ' d blocks)
Illegal access to stacks (reading/writing inappropriate areas on the stack)
Whether the requested space has been released (Memory leaks-where pointers to malloc ' d blocks is lost forever)
Malloc/free/new/delete application and Release memory matching (mismatched use of malloc/new/new [] vs Free/delete/delete [])
SRC and DST overlap (overlapping src and DST pointers in memcpy () and related functions)
Repeat free
1. Compile and install Valgrind:
wget http://valgrind.org/downloads/valgrind-3.4.1.tar.bz2
Tar xvf valgrind-3.4.1.tar.bz2
CD VALGRIND-3.4.1/
./configure--prefix=/usr/local/webserver/valgrind
Make
Make install
2, use example: to the "LS" program process check, return the results of "definitely lost:0 bytes in 0 blocks." Indicates no memory leak.
[Email protected]/]#/usr/local/webserver/valgrind/bin/valgrind--tool=memcheck--leak-check=full ls/
==1157== Memcheck, a memory error detector.
==1157== Copyright (C) 2002-2008, and GNU GPL ' d, by Julian Seward et al.
==1157== Using Libvex Rev 1884, a library for dynamic binary translation.
==1157== Copyright (C) 2004-2008, and GNU GPL ' d, by Openworks LLP.
==1157== Using valgrind-3.4.1, a dynamic binary instrumentation framework.
==1157== Copyright (C) 2000-2008, and GNU GPL ' d, by Julian Seward et al.
==1157== for more details, rerun with:-V
==1157==
Bin Data0 Dev Home lib64 media mnt opt root selinux sys tcsql.db.idx.pkey.dec ttserver.pid var
Boot Data1 etc lib Lost+found misc net proc sbin SRV tcsql.db tmp usr
==1157==
==1157== ERROR summary:0 errors from 0 contexts (Suppressed:5 from 1)
==1157== malloc/free:in use at exit:28,471 bytes in blocks.
==1157== malloc/free:166 Allocs, Frees, 51,377 bytes allocated.
==1157== for counts of detected errors, rerun with:-V
==1157== searching for pointers to not-freed blocks.
==1157== checked 174,640 bytes.
==1157==
==1157== LEAK SUMMARY:
==1157== definitely lost:0 bytes in 0 blocks.
==1157== possibly lost:0 bytes in 0 blocks.
==1157== still reachable:28,471 bytes in blocks.
==1157== suppressed:0 bytes in 0 blocks.
==1157== Reachable blocks (those to which a pointer is found) is not shown.
==1157== to see them, rerun with:--leak-check=full--show-reachable=yes
3. Use example: a "httptest" program process check written using the Libevent library returns "definitely lost:255 bytes in 5 blocks." Indicates a memory leak occurred.
[Email protected] tcsql-0.1]#/usr/local/webserver/valgrind/bin/valgrind--tool=memcheck--leak-check=full. Httptest
==1274== Memcheck, a memory error detector.
==1274== Copyright (C) 2002-2008, and GNU GPL ' d, by Julian Seward et al.
==1274== Using Libvex Rev 1884, a library for dynamic binary translation.
==1274== Copyright (C) 2004-2008, and GNU GPL ' d, by Openworks LLP.
==1274== Using valgrind-3.4.1, a dynamic binary instrumentation framework.
==1274== Copyright (C) 2000-2008, and GNU GPL ' d, by Julian Seward et al.
==1274== for more details, rerun with:-V
==1274==
==1274== ERROR summary:0 errors from 0 contexts (suppressed:1005 from 2)
==1274== malloc/free:in use at exit:402,291 bytes in blocks.
==1274== malloc/free:15,939 Allocs, 15,865 Frees, 6,281,523 bytes allocated.
==1274== for counts of detected errors, rerun with:-V
==1274== searching for pointers to not-freed blocks.
==1274== checked 682,468,160 bytes.
==1274==
==1274== 255 bytes in 5 blocks is definitely lost in loss record 32
==1274== at 0x4a05fbb:malloc (vg_replace_malloc.c:207)
==1274== by 0x3c1d809bc6:evhttp_decode_uri (http.c:2105)
==1274== by 0x401c75:tcsql_handler (In/data0/tcsql/cankao/tcsql-0.1/tcsql)
==1274== by 0x3c1d80c88f:evhttp_get_body (http.c:1582)
==1274== by 0x3c1d8065f7:event_base_loop (event.c:392)
==1274== by 0x403e2f:main (In/data0/tcsql/cankao/tcsql-0.1/tcsql)
==1274==
==1274== LEAK SUMMARY:
==1274== definitely lost:255 bytes in 5 blocks.
==1274== possibly lost:0 bytes in 0 blocks.
==1274== still reachable:402,036 bytes in blocks.
==1274== suppressed:0 bytes in 0 blocks.
==1274== Reachable blocks (those to which a pointer is found) is not shown.
==1274== to see them, rerun with:--leak-check=full--show-reachable=yes
Check the Httptest program and find that there is a "char *decode_uri = Evhttp_decode_uri (Evhttp_request_uri (req));" The "Decode_uri" in the "no" is not free, and then the process is completed, and then add the "Decode_uri"; , and then using the Valgrind check, the result is already "definitely lost:0 bytes in 0 blocks."
Linux/C + + memory leak Detection Tool: Valgrind
