爲什麼valgrind沒有在我的「測試」程序中檢測到內存泄漏？

整個測試代碼包含在main.cpp中，如下所示：爲什麼valgrind沒有在我的「測試」程序中檢測到內存泄漏？

#include <iostream> 

using std::cout; 
using std::endl; 

void f(int i) { 
    int* pi = new int; 

    *pi = i; 

    std::cout << "*pi = " << *pi << std::endl; 
} 

int main(int argc, char *argv[]) { 
    int i = 0; 

    while (i < 10000) { 
     f(i); 
     ++i; 
    } 

    return 0; 
}

予編譯沒有優化-O0（從一個Eclipse Qt工程）其中：

g++ -c -pipe -O0 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -Irelease -o release/main.o main.cpp

然後作爲鏈接如下：

g++ -Wl,-O0 -o test release/main.o -L/usr/lib -lQtGui -lQtCore -lpthread

我的valgrind通過運行可執行文件，並得到下面的輸出：

laptop:~/workspace/test$ valgrind --leak-check=yes test 
==3939== Memcheck, a memory error detector 
==3939== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. 
==3939== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info 
==3939== Command: test 
==3939== 
==3939== 
==3939== HEAP SUMMARY: 
==3939==  in use at exit: 0 bytes in 0 blocks 
==3939== total heap usage: 1,387 allocs, 1,387 frees, 64,394 bytes allocated 
==3939== 
==3939== All heap blocks were freed -- no leaks are possible 
==3939== 
==3939== For counts of detected and suppressed errors, rerun with: -v 
==3939== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 13 from 8)

我相信Valgrind把報告內存泄漏，而不是沒有任何泄漏，因爲在呼叫分配給new int

編輯的堆內存是可能的：改變上面的代碼使用std ::法院，而不是qDebug （）具有相同的結果

如果我編譯和鏈接相同的代碼（從一個Eclipse CDT項目），沒有Qt的依賴，Valgrind的檢測泄漏：

g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp" 

g++ -o"test2" ./main.o 

==4604== HEAP SUMMARY: 
==4604==  in use at exit: 40,000 bytes in 10,000 blocks 
==4604== total heap usage: 10,000 allocs, 0 frees, 40,000 bytes allocated 
==4604== 
==4604== 40,000 bytes in 10,000 blocks are definitely lost in loss record 1 of 1 
==4604== at 0x402569A: operator new(unsigned int) (vg_replace_malloc.c:255) 
==4604== by 0x8048756: f(int) (main.cpp:7) 
==4604== by 0x80487BB: main (main.cpp:18) 
==4604== 
==4604== LEAK SUMMARY: 
==4604== definitely lost: 40,000 bytes in 10,000 blocks 
==4604== indirectly lost: 0 bytes in 0 blocks 
==4604==  possibly lost: 0 bytes in 0 blocks 
==4604== still reachable: 0 bytes in 0 blocks 
==4604==   suppressed: 0 bytes in 0 blocks 
==4604== 
==4604== For counts of detected and suppressed errors, rerun with: -v 
==4604== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 19 from 8)

我ü唱Kubuntu 10.04 32位，並嘗試調試和發佈構建，我做錯了什麼或爲什麼valgrind報告與Qt鏈接時的內存泄漏？

來源

2011-01-24 Peter McG

但願這是編譯器消除了代碼，因爲它認爲沒有效果呢？ – sharptooth 2011-01-24 08:43:22

@sharptooth：我不這麼認爲，因爲在調試模式下qDebug寫入標準輸出這是一個副作用，應該防止編譯器消除？我也嘗試過`std :: cout`而不是`qDebug`（這個調用在release中被刪除）並得到相同的結果。你和我有同樣的結果嗎？ – 2011-01-24 08:51:40

我還沒有試過這段代碼。但對我來說，看起來應該報告泄漏，並且我可以假設它沒有報告的兩個原因 - 編譯器優化或堆干擾valgrind的特殊實現。 – sharptooth 2011-01-24 08:54:21

發生這種情況的原因是，調用：

valgrind --leak-check=yes test

實際上是在/ usr/bin/test上運行valgrind，它是一個內置程序，用於檢查文件類型並比較值，所有我需要的是：

valgrind --leak-check=yes ./test

來源

2011-01-24 09:49:21

我已經取代qDebug（）中std ::法院：

==2426== HEAP SUMMARY: 
==2426==  in use at exit: 40,000 bytes in 10,000 blocks 
==2426== total heap usage: 10,000 allocs, 0 frees, 40,000 bytes allocated 
==2426== 
==2426== LEAK SUMMARY: 
==2426== definitely lost: 39,996 bytes in 9,999 blocks

來源

2011-01-24 08:50:08 knivil

當我使用你的代碼和編譯器選項時，沒有什麼改變。也許這是Eclipse的錯。 – knivil 2011-01-24 09:25:28

可能是你的編譯器消除優化的代碼，嘗試用-O0編譯（沒有優化選項）。

至於評論，與Debian的-O2 lenny中，檢測到泄漏：

==20547== LEAK SUMMARY: 
==20547== definitely lost: 40,000 bytes in 10,000 blocks. 
==20547==  possibly lost: 0 bytes in 0 blocks. 
==20547== still reachable: 516 bytes in 7 blocks. 
==20547==   suppressed: 0 bytes in 0 blocks. 
==20547== Rerun with --leak-check=full to see details of leaked memory.

編譯器：

gcc version 4.3.2 (Debian 4.3.2-1.1)

來源

2011-01-24 08:57:16

爲什麼valgrind沒有在我的「測試」程序中檢測到內存泄漏？

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