Question

如何正确关闭并释放ALSA（和hw params）资源？我找到了很多例子。各不相同。所有人都有memleak。

例如：

#include <stdio.h>
#include <unistd.h>
#include <alsa/asoundlib.h>

int
main()
{
    snd_pcm_t *dev;

    snd_pcm_open(&dev, "default", SND_PCM_STREAM_PLAYBACK, 0);
    snd_pcm_close(dev);

    return 0;
}

Valgrind报告：

==19586== LEAK SUMMARY:
==19586==    definitely lost: 0 bytes in 0 blocks
==19586==    indirectly lost: 0 bytes in 0 blocks
==19586==      possibly lost: 65,525 bytes in 2,020 blocks
==19586==    still reachable: 298 bytes in 6 blocks
==19586==         suppressed: 0 bytes in 0 blocks
==19586== Reachable blocks (those to which a pointer was found) are not shown.
==19586== To see them, rerun with: --leak-check=full --show-reachable=yes
==19586== 
==19586== ERROR SUMMARY: 116 errors from 116 contexts (suppressed: 4 from 4)
--19586-- 
--19586-- used_suppression:      2 dl-hack3-cond-1
--19586-- used_suppression:      2 glibc-2.5.x-on-SUSE-10.2-(PPC)-2a
==19586== 
==19586== ERROR SUMMARY: 116 errors from 116 contexts (suppressed: 4 from 4)

UPD：

没有snd_pcm_close（），我们在117个上下文中有117个错误）））

Answer 1

如果您通过调用snd_config_update_free_global（）来释放全局配置，那么您将无法获得泄漏：snd_pcm_close（handle）;

Answer 2

使用alsalib 1.1.4.1测试此示例：

#include <stdio.h>
#include <unistd.h>
#include <alsa/asoundlib.h>

int main()
{
    snd_pcm_t *dev;

    snd_pcm_open(&dev, "default", SND_PCM_STREAM_PLAYBACK, 0);
    snd_pcm_close(dev);
    snd_config_update_free_global();

    return 0;
}

根据Paolo的建议添加snd_config_update_free_global（），valgrind会显示很多这样的警告：

4,320 bytes in 60 blocks are possibly lost in loss record 91 of 94

摘要显示可能丢失的块：

==499== LEAK SUMMARY:
==499==    definitely lost: 0 bytes in 0 blocks
==499==    indirectly lost: 0 bytes in 0 blocks
==499==      possibly lost: 43,011 bytes in 1,311 blocks
==499==    still reachable: 111,131 bytes in 128 blocks
==499==         suppressed: 0 bytes in 0 blocks
==499== Reachable blocks (those to which a pointer was found) are not shown.
==499== To see them, rerun with: --leak-check=full --show-leak-kinds=all

可以做些什么？

如何正确关闭和释放ALSA资源

2 个答案: