How to allocate thread local storage?

Question

I have a variable in my function that is static, but I would like it to be static on a per thread basis.

How can I allocate the memory for my C++ class such that eac

Answer 1

Folly (Facebook Open-source Library) has a portable implementation of Thread Local Storage.

According its authors:

Improved thread local storage for non-trivial types (similar speed as pthread_getspecific but only consumes a single pthread_key_t, and 4x faster than boost::thread_specific_ptr).

If your looking for a portable implementation of Local Storage Thread, this library is a good option.

Answer 2

C++11 specifies a thread_local storage type, just use it.

AnotherClass::threadSpecificAction()
{
  thread_local MyClass *instance = new MyClass();
  instance->doSomething();
}

One optional optimization is to also allocate on thread local storage.

Answer 3

#include <boost/thread/tss.hpp>
static boost::thread_specific_ptr< MyClass> instance;
if( ! instance.get() ) {
    // first time called by this thread
    // construct test element to be used in all subsequent calls from this thread
    instance.reset( new MyClass);
}
    instance->doSomething();