Method: Thread#thread_variable_get

Defined in:

thread.c

#thread_variable_get(key) ⇒ Object^?

Returns the value of a thread local variable that has been set. Note that these are different than fiber local values. For fiber local values, please see Thread#[] and Thread#[]=.

Thread local values are carried along with threads, and do not respect fibers. For example:

Thread.new {
  Thread.current.thread_variable_set("foo", "bar") # set a thread local
  Thread.current["foo"] = "bar"                    # set a fiber local

  Fiber.new {
    Fiber.yield [
      Thread.current.thread_variable_get("foo"), # get the thread local
      Thread.current["foo"],                     # get the fiber local
    ]
  }.resume
}.join.value # => ['bar', nil]

The value “bar” is returned for the thread local, where nil is returned for the fiber local. The fiber is executed in the same thread, so the thread local values are available.

Returns:

• (Object, nil)

# File 'thread.c', line 3778

static VALUE
rb_thread_variable_get(VALUE thread, VALUE key)
{
    VALUE locals;
    VALUE symbol = rb_to_symbol(key);

    if (LIKELY(!THREAD_LOCAL_STORAGE_INITIALISED_P(thread))) {
        return Qnil;
    }
    locals = rb_thread_local_storage(thread);
    return rb_hash_aref(locals, symbol);
}