使用boost日志，Valgrind检查内存泄漏

Question

测试代码：

#include <iostream>
#include <boost/log/trivial.hpp>
using namespace std;
int main()
{
        cout << "hello, world" << endl;
        BOOST_LOG_TRIVIAL(trace) << "A trace severity message";
        BOOST_LOG_TRIVIAL(debug) << "A debug severity message";
        BOOST_LOG_TRIVIAL(info) << "An informational severity message";
        BOOST_LOG_TRIVIAL(warning) << "A warning severity message";
        BOOST_LOG_TRIVIAL(error) << "An error severity message";
        BOOST_LOG_TRIVIAL(fatal) << "A fatal severity message";
        return 0;
}

编译

g++ -Wall -DBOOST_LOG_DYN_LINK -o ./main.o -c ./main.cc
g++ ./main.o -o main -rdynamic -Wl,-rpath=/usr/local/lib -lpthread -lboost_log -lboost_system -lboost_thread -lboost_filesystem
valgrind --leak-check=full --show-reachable=yes --trace-children=yes --log-file=mem.log ./main

mem.log，如下所示：

==29900== 8 bytes in 1 blocks are still reachable in loss record 1 of 6
==29900==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)
==29900==    by 0x4C8D04B: boost::log::v2_mt_posix::aux::this_thread::get_id() (in /usr/local/lib/libboost_log.so.1.56.0)
==29900== 8 bytes in 1 blocks are still reachable in loss record 2 of 6
==29900==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)
==29900==    by 0x4C8751C: boost::log::v2_mt_posix::sources::aux::get_severity_level() (in /usr/local/lib/libboost_log.so.1.56.0)
==29900== 16 bytes in 1 blocks are still reachable in loss record 3 of 6
==29900==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)
==29900==    by 0x511ADD2: boost::detail::add_thread_exit_function(boost::detail::thread_exit_function_base*) (in /usr/local/lib/libboost_thread.so.1.56.0)
==29900== 24 bytes in 1 blocks are still reachable in loss record 4 of 6
==29900==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)
==29900==    by 0x511A44C: boost::detail::make_external_thread_data() (in /usr/local/lib/libboost_thread.so.1.56.0)
==29900== 24 bytes in 1 blocks are still reachable in loss record 5 of 6
==29900==    at 0x4A06019: operator new(unsigned long) (vg_replace_malloc.c:167)
==29900==    by 0x4C87569: boost::log::v2_mt_posix::sources::aux::get_severity_level() (in /usr/local/lib/libboost_log.so.1.56.0)
 ==29900== LEAK SUMMARY: 
 ==29900==    definitely lost: 0 bytes in 0 blocks. 
 ==29900==      possibly lost: 0 bytes in 0 blocks. 
 ==29900==    still reachable: 520 bytes in 6 blocks. 
 ==29900==         suppressed: 0 bytes in 0 blocks.

Answer 1

报告的唯一问题是"仍然可以到达"的问题，这些问题并不总是真正的问题。Valgrind是一个很好的工具，但这个特定类别（--show-reachable）对大多数人来说并不有用。你应该简单地停止使用这个选项，因为它并没有向你显示任何你真正需要修复的东西。

来自之前的讨论：

"仍然可以访问"意味着你的程序可能还可以——它没有释放出一些可能有的内存。这是很常见的，而且往往是合理的。如果您不想看到这些报告，请不要使用--show reachable=yes。