我一直在追逐内存泄漏（由'valgrind --leak-check = yes'报告），它似乎来自ALSA。这段代码已经在自由世界中存在了一段时间，所以我猜这是我做错了。
#include <stdio.h>
#include <stdlib.h>
#include <alsa/asoundlib.h>
int main (int argc, char *argv[])
{
snd_ctl_t *handle;
int err = snd_ctl_open( &handle, "hw:1", 0 );
printf( "snd_ctl_open: %d\n", err );
err = snd_ctl_close(handle);
printf( "snd_ctl_close: %d\n", err );
}
输出如下：
[root@aeolus alsa]# valgrind --leak-check=yes ./test2
==16296== Memcheck, a memory error detector
==16296== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==16296== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==16296== Command: ./test2
==16296==
snd_ctl_open: 0
snd_ctl_close: 0
==16296==
==16296== HEAP SUMMARY:
==16296== in use at exit: 22,912 bytes in 1,222 blocks
==16296== total heap usage: 1,507 allocs, 285 frees, 26,236 bytes allocated
==16296==
==16296== 4 bytes in 2 blocks are possibly lost in loss record 1 of 62
==16296== at 0x4007100: malloc (vg_replace_malloc.c:270)
==16296== by 0x340F7F: strdup (in /lib/libc-2.5.so)
==16296== by 0x624C6B5: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624CA5B: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624CD81: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624F311: snd_config_update_r (in /lib/libasound.so.2.0.0)
==16296== by 0x624FAD7: snd_config_update (in /lib/libasound.so.2.0.0)
==16296== by 0x625DA22: snd_ctl_open (in /lib/libasound.so.2.0.0)
==16296== by 0x804852F: main (test2.cpp:9)
并继续浏览某些页面
==16296== 2,052 bytes in 57 blocks are possibly lost in loss record 62 of 62
==16296== at 0x4005EB4: calloc (vg_replace_malloc.c:593)
==16296== by 0x624A268: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624A38F: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624CA33: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624CCC9: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624CD81: ??? (in /lib/libasound.so.2.0.0)
==16296== by 0x624F311: snd_config_update_r (in /lib/libasound.so.2.0.0)
==16296== by 0x624FAD7: snd_config_update (in /lib/libasound.so.2.0.0)
==16296== by 0x625DA22: snd_ctl_open (in /lib/libasound.so.2.0.0)
==16296== by 0x804852F: main (test2.cpp:9)
==16296==
==16296== LEAK SUMMARY:
==16296== definitely lost: 0 bytes in 0 blocks
==16296== indirectly lost: 0 bytes in 0 blocks
==16296== possibly lost: 22,748 bytes in 1,216 blocks
==16296== still reachable: 164 bytes in 6 blocks
==16296== suppressed: 0 bytes in 0 blocks
==16296== Reachable blocks (those to which a pointer was found) are not shown.
==16296== To see them, rerun with: --leak-check=full --show-reachable=yes
==16296==
==16296== For counts of detected and suppressed errors, rerun with: -v
==16296== ERROR SUMMARY: 56 errors from 56 contexts (suppressed: 19 from 8)
这是因为我在一个项目中使用ALSA并开始看到这个巨大的泄漏......或者至少是泄漏的报告。
所以问题是：是我，ALSA还是valgrind，这里有问题？
答案 0 :(得分：3)
http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=MEMORY-LEAK;hb=HEAD说：
Memory leaks - really? ----------------------请注意，一些开发人员认为ALSA库有一些内存 泄漏。当然，这可能是事实，但在联系我们之前，请确保 这些泄漏不是强迫的。
报告的最大泄漏是缓存全局配置 下次使用。如果您不想要此功能，只需致电 所有snd _ * _ open *（）调用之后的snd_config_update_free_global（）。这个功能 将释放缓存。
答案 1 :(得分：1)
报告的最大漏洞是全局配置被缓存以供下次使用。
如果您不想要此功能，只需在所有snd_config_update_free_global()来电后拨打snd_*_open*()即可。
此功能将释放缓存。“＆lt; ---- Valgrind仍会检测到泄漏。
如果您在 snd_config_update_free_global()
snd_pcm_close(handle); ，则可以修复此问题
答案 2 :(得分：0)
也许这会奏效（source）：
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -2171,7 +2171,12 @@ static int snd_pcm_open_conf(snd_pcm_t **pcmp, const char *name,
if (open_func) {
err = open_func(pcmp, name, pcm_root, pcm_conf, stream, mode);
if (err >= 0) {
- (*pcmp)->open_func = open_func;
+ if ((*pcmp)->open_func) {
+ /* only init plugin (like empty, asym) */
+ snd_dlobj_cache_put(open_func);
+ } else {
+ (*pcmp)->open_func = open_func;
+ }
err = 0;
} else {
snd_dlobj_cache_put(open_func);
我自己尝试过，但无济于事。我的核心温度加热~10°F，很可能是由于类似的内存泄漏。以下是 valgrind 给我的一些内容，即使在使用上面的补丁之后：
==869== 16,272 bytes in 226 blocks are possibly lost in loss record 103 of 103
==869== at 0x4C28E48: calloc (vg_replace_malloc.c:566)
==869== by 0x5066E61: _snd_config_make (in /usr/lib64/libasound.so.2)
==869== by 0x5066F58: _snd_config_make_add (in /usr/lib64/libasound.so.2)
==869== by 0x50673B9: parse_value (in /usr/lib64/libasound.so.2)
==869== by 0x50675DE: parse_array_def (in /usr/lib64/libasound.so.2)
==869== by 0x5067680: parse_array_defs (in /usr/lib64/libasound.so.2)
==869== by 0x5067A8E: parse_def (in /usr/lib64/libasound.so.2)
==869== by 0x5067BC7: parse_defs (in /usr/lib64/libasound.so.2)
==869== by 0x5067A6F: parse_def (in /usr/lib64/libasound.so.2)
==869== by 0x5067BC7: parse_defs (in /usr/lib64/libasound.so.2)
==869== by 0x5067A6F: parse_def (in /usr/lib64/libasound.so.2)
==869== by 0x5067BC7: parse_defs (in /usr/lib64/libasound.so.2)
丢失的字节数不断增加。