Recent GCC, e.g. GCC 5 do support C11 and its thread_local (if compiling with e.g. gcc -std=c11). As FUZxxl commented, you could use (instead of C11 thread_local) the __thread qualifier supported by older GCC versions. Read about Thread Local Storage. pthread_getspecific is indeed quite slow (it is in the POSIX library, so is not provided … Read more
It’s a little complicated (this document explains it in great detail), but it’s basically neither. Instead the compiler puts a special .tdata section in the executable, which contains all the thread-local variables. At runtime, a new data section for each thread is created with a copy of the data in the (read-only) .tdata section, and … Read more
The speed depends on the TLS implementation. Yes, you are correct that TLS can be as fast as a pointer lookup. It can even be faster on systems with a memory management unit. For the pointer lookup you need help from the scheduler though. The scheduler must – on a task switch – update the … Read more
The Go runtime and standard libraries do not provide goroutine local storage or a goroutine identifier that can be used to implement goroutine local storage. The third party gls package implements goroutine local storage in an interesting way. Some find this package horrifying and others think it’s clever. The Go team recommends passing context explicitly … Read more
#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();
Thread local storage is useful for instance if you have a thread worker pool and each thread needs access to its own resource, like a network or database connection. Note that the threading module uses the regular concept of threads (which have access to the process global data), but these are not too useful due … Read more
According to the C++ Standard When thread_local is applied to a variable of block scope the storage-class-specifier static is implied if it does not appear explicitly So it means that this definition void f() { thread_local vector<int> V; V.clear(); … // use V as a temporary variable } is equivalent to void f() { static … Read more
Thread-local storage duration is a term used to refer to data that is seemingly global or static storage duration (from the viewpoint of the functions using it) but, in actual fact, there is one copy per thread. It adds to the current options: automatic (exists during a block or function); static (exists for the program … Read more