thread_local 变量何时以及如何初始化和销毁？
When and how are thread_local variables initialized and destroyed?
在我的代码中使用它之前，我想更好地理解 thread_local。
比方说，我声明
thread_local myclass value;
那将为每个使用 value 的线程创建 myclass 的新实例？线程退出时会发生什么？该实例会被释放还是会保留在内存中的某个地方？什么时候调用析构函数？
是否thread_local锁定构造函数以便在任何时刻只能调用一个构造函数？
[basic.stc.thread]/1 All variables declared with the thread_local keyword have thread storage duration. The storage for these entities shall last for the duration of the thread in which they are created. There is a distinct object or reference per thread, and use of the declared name refers to the entity associated with the current thread.
[basic.stc.thread]/2 A variable with thread storage duration shall be initialized before its first odr-use (6.2) and, if constructed, shall be destroyed on thread exit.
不，构造函数调用没有自动同步。 None 是必需的，因为只有一个线程可能会尝试构造给定的线程局部对象。
根据this storage duration reference一个thread_local变量：
... is allocated when the thread begins and deallocated when the thread ends.
所以是的，当线程结束时，该线程的 thread_local 变量的生命周期也结束，这意味着这些特定实例将被销毁。
在我的代码中使用它之前，我想更好地理解 thread_local。
比方说，我声明
thread_local myclass value;
那将为每个使用 value 的线程创建 myclass 的新实例？线程退出时会发生什么？该实例会被释放还是会保留在内存中的某个地方？什么时候调用析构函数？
是否thread_local锁定构造函数以便在任何时刻只能调用一个构造函数？
[basic.stc.thread]/1 All variables declared with the
thread_localkeyword have thread storage duration. The storage for these entities shall last for the duration of the thread in which they are created. There is a distinct object or reference per thread, and use of the declared name refers to the entity associated with the current thread.[basic.stc.thread]/2 A variable with thread storage duration shall be initialized before its first odr-use (6.2) and, if constructed, shall be destroyed on thread exit.
不，构造函数调用没有自动同步。 None 是必需的，因为只有一个线程可能会尝试构造给定的线程局部对象。
根据this storage duration reference一个thread_local变量：
... is allocated when the thread begins and deallocated when the thread ends.
所以是的，当线程结束时，该线程的 thread_local 变量的生命周期也结束，这意味着这些特定实例将被销毁。