Valgrind通过以下代码报告泄漏的块，显然每个线程一个：
#include <iostream>
#include <thread>
#include <mutex>
#include <list>
#include <chrono>
std::mutex cout_mutex;
struct Foo
{
Foo()
{
std::lock_guard<std::mutex> lock( cout_mutex );
std::cout << __PRETTY_FUNCTION__ << '\n';
}
~Foo()
{
std::lock_guard<std::mutex> lock( cout_mutex );
std::cout << __PRETTY_FUNCTION__ << '\n';
}
void
hello_world()
{
std::lock_guard<std::mutex> lock( cout_mutex );
std::cout << __PRETTY_FUNCTION__ << '\n';
}
};
void
hello_world_thread()
{
thread_local Foo foo;
// must access, or the thread local variable may not be instantiated
foo.hello_world();
// keep the thread around momentarily
std::this_thread::sleep_for( std::chrono::milliseconds( 100 ) );
}
int main()
{
for ( int i = 0; i < 100; ++i )
{
std::list<std::thread> threads;
for ( int j = 0; j < 10; ++j )
{
std::thread thread( hello_world_thread );
threads.push_back( std::move( thread ) );
}
while ( ! threads.empty() )
{
threads.front().join();
threads.pop_front();
}
}
}
编译器版本：
$ g++ --version
g++ (GCC) 4.8.1
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
GCC构建选项：
--enable-shared
--enable-threads=posix
--enable-__cxa_atexit
--enable-clocale=gnu
--enable-cxx-flags='-fno-omit-frame-pointer -g3'
--enable-languages=c,c++
--enable-libstdcxx-time=rt
--enable-checking=release
--enable-build-with-cxx
--disable-werror
--disable-multilib
--disable-bootstrap
--with-system-zlib
程序编译选项：
g++ -std=gnu++11 -Og -g3 -Wall -Wextra -fno-omit-frame-pointer thread_local.cc
valgrind版本：
$ valgrind --version
valgrind-3.8.1
Valgrind选项：
valgrind --leak-check=full --verbose ./a.out > /dev/null
valgrind输出的尾端：
==1786== HEAP SUMMARY:
==1786== in use at exit: 24,000 bytes in 1,000 blocks
==1786== total heap usage: 3,604 allocs, 2,604 frees, 287,616 bytes allocated
==1786==
==1786== Searching for pointers to 1,000 not-freed blocks
==1786== Checked 215,720 bytes
==1786==
==1786== 24,000 bytes in 1,000 blocks are definitely lost in loss record 1 of 1
==1786== at 0x4C29969: operator new(unsigned long, std::nothrow_t const&) (vg_replace_malloc.c:329)
==1786== by 0x4E8E53E: __cxa_thread_atexit (atexit_thread.cc:119)
==1786== by 0x401036: hello_world_thread() (thread_local.cc:34)
==1786== by 0x401416: std::thread::_Impl<std::_Bind_simple<void (*())()> >::_M_run() (functional:1732)
==1786== by 0x4EE4830: execute_native_thread_routine (thread.cc:84)
==1786== by 0x5A10E99: start_thread (pthread_create.c:308)
==1786== by 0x573DCCC: clone (clone.S:112)
==1786==
==1786== LEAK SUMMARY:
==1786== definitely lost: 24,000 bytes in 1,000 blocks
==1786== indirectly lost: 0 bytes in 0 blocks
==1786== possibly lost: 0 bytes in 0 blocks
==1786== still reachable: 0 bytes in 0 blocks
==1786== suppressed: 0 bytes in 0 blocks
==1786==
==1786== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
--1786--
--1786-- used_suppression: 2 dl-hack3-cond-1
==1786==
==1786== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
构造函数和析构函数对每个线程运行一次：
$ ./a.out | grep 'Foo::Foo' | wc -l
1000
$ ./a.out | grep hello_world | wc -l
1000
$ ./a.out | grep 'Foo::~Foo' | wc -l
1000
笔记：
如果更改创建的线程数，则泄漏的块数与线程数匹配。
如果以这样的方式实现GCC，则代码的结构可能允许资源重用（即泄漏的块）。
在valgrind堆栈跟踪中，thread_local.cc：34是以下行：
thread_local Foo foo;由于sleep_for（）调用，程序运行大约需要10秒钟左右。
您是否知道此内存泄漏是由于GCC，我的配置选项导致的还是我的程序中存在某些错误？
最佳答案
似乎泄漏来自动态初始化。
这是int的示例：
thread_local int num=4; //static initialization
最后一个示例不泄漏。我尝试了2个线程，完全没有泄漏。
但现在 ：
int func()
{
return 4;
}
thread_local int num2=func(); //dynamic initialization
这一个漏！具有2个线程，它给出
total heap uage: 8 allocs, 6 frees, 428 bytes allocated ...我建议您使用类似的解决方法：
thread_local Foo *foo = new Foo; //dynamic initialization
不要忘记在线程执行结束时执行以下操作：
delete foo;
但是最后一个例子是一个问题：如果在删除之前线程退出并出现错误怎么办？再次泄漏...
似乎没有很好的解决方案。也许我们应该就此向
g++开发人员报告？关于c++11 - 使用thread_local时在gcc 4.8.1中发生内存泄漏？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17668729/