This section introduces threads, which are Ruby’s control structure for concurrent execution, and also two more esoteric control structures, called fibers and continuations.
A thread of execution is a sequence of Ruby statements that run (or appear to
run) in parallel with the main sequence of statements that the
interpreter is running. Threads are represented by
Thread objects, but they can also be thought
of as control structures for concurrency. Concurrent programming in
Ruby is covered in detail in Threads and Concurrency. This section
is just a simple overview that shows how to create threads.
Ruby’s use of blocks makes it very easy to create new threads.
and associate a block with it. A new thread of execution
will be created and will start running the code in the block.
Meanwhile, the original thread will return from the
Thread.new call and will continue with the
following statement. The newly created thread will exit when the block
exits. The return value of the block becomes available through the
value method of the
Thread object. (If you call this method
before the thread has completed, the caller will block until the
thread returns a value.)
The following code shows how you might use threads to read the contents of multiple files in parallel:
# This method expects an array of filenames. # It returns an array of strings holding the content of the named files. # The method creates one thread for ...