10

我在 Ubuntu 12.04（精确）64 位上使用 R 2.15.3。如果我在 valgrind 中运行 R：

R -d "valgrind" --香草

然后我使用 q() 退出程序并得到以下报告：

==7167== HEAP SUMMARY:
==7167==     in use at exit: 28,239,464 bytes in 12,512 blocks
==7167==   total heap usage: 28,780 allocs, 16,268 frees, 46,316,337 bytes allocated
==7167== 
==7167== LEAK SUMMARY:
==7167==    definitely lost: 120 bytes in 2 blocks
==7167==    indirectly lost: 480 bytes in 20 blocks
==7167==      possibly lost: 0 bytes in 0 blocks
==7167==    still reachable: 28,238,864 bytes in 12,490 blocks
==7167==         suppressed: 0 bytes in 0 blocks
==7167== Rerun with --leak-check=full to see details of leaked memory
==7167== 
==7167== For counts of detected and suppressed errors, rerun with: -v
==7167== Use --track-origins=yes to see where uninitialised values come from
==7167== ERROR SUMMARY: 385 errors from 5 contexts (suppressed: 2 from 2)

最近 R 经常崩溃，尤其是当我通过 Rcpp 调用 C++ 函数时，这可能是原因吗？谢谢！

4

1 回答 1

10

您可能误读了 valgrind 输出。最有可能的是，这里没有（明显的）泄漏，因为 R 作为一个系统进行了很好的研究。然而，R 是一种动态类型的语言，它当然已经完成了分配。“肯定丢失：120 字节”本质上是测量错误——请参阅 valgrind 文档。

如果您想查看泄漏，请创建一个，例如，使用如下文件：

library(Rcpp)
cppFunction('int leak(int N) {double *ptr = (double*) malloc(N*sizeof(double)); \
             return 0;}')
leak(10000)

它保留内存，甚至明确地超出 R 的范围，然后退出。在这里我们得到：

$ R -d "valgrind" -f /tmp/leak.R
[...]
R> leak(10000)
[1] 0
R> 
==4479== 
==4479== HEAP SUMMARY:
==4479==     in use at exit: 35,612,126 bytes in 15,998 blocks
==4479==   total heap usage: 47,607 allocs, 31,609 frees, 176,941,927 bytes allocated
==4479== 
==4479== LEAK SUMMARY:
==4479==    definitely lost: 120 bytes in 2 blocks
==4479==    indirectly lost: 480 bytes in 20 blocks
==4479==      possibly lost: 0 bytes in 0 blocks
==4479==    still reachable: 35,611,526 bytes in 15,976 blocks
==4479==         suppressed: 0 bytes in 0 blocks
==4479== Rerun with --leak-check=full to see details of leaked memory
==4479== 
==4479== For counts of detected and suppressed errors, rerun with: -v
==4479== Use --track-origins=yes to see where uninitialised values come from
==4479== ERROR SUMMARY: 31 errors from 10 contexts (suppressed: 2 from 2)
$

现在有更多的泄漏（尽管它仍然不像人们希望的那样容易阅读）。如果您添加建议的标志，它将最终指向malloc()我们所做的调用。

此外，在我的“带 R 的 HPC 简介”幻灯片组中，我有一个 CRAN 包的早期版本中实际泄漏的工作示例。如果有泄漏，这会有所帮助。如果没有，就很难看穿噪音。

所以简而言之，如果你的代码崩溃了，那可能是你的代码的错。尝试一个最小的可重现示例是（好的）标准建议。

于 2013-05-03T14:10:59.010 回答