Which ruby methods free GVL?

Question

In multi-threaded ruby execution, you cannot get parallel execution of threads unless you use those functions which frees GVL.

In my understanding, following ruby methods frees GVL:

• Kernel#sleep
• IO#read and IO#write

Question

• In pure ruby, is there any other methods which frees GVL?

Version

• I'm currently using ruby version 2.6, so expect the info of this version.

Answer 1

I asked same question on stackoverflow (Japanese).

Got this answer https://ja.stackoverflow.com/a/55579/754 , which stating that

• Bignum's div / modulo
• Dir.new/Dir.open
• Dir.chdir
• Dir.rmdir
• Dir.empty?
• Dir.glob
• File.chown
• File's methods which check file status, namely stats
• File.rename
• File.truncate
• File.mkfifo
• IO.copy_stream
• IO.#open and IO.#close related codes (was too complex to understand)
• Kernel.#system
• Kernel.#exec

and in other standard libraries such as fiddle, openssl, readline, socket, zlib actually calls method which frees GVL.

this great answer was written by https://stackoverflow.com/users/4944814/raccy

Answer 2

In pure ruby, is there any other methods which frees GVL?

In pure Ruby, there is no such thing as a GVL. The GVL is a feature of some specific versions of one specific implementation of Ruby. The vast majority of Ruby implementations don't have a GVL or even something remotely similar.

I'm currently using ruby version 2.6, so expect the info of this version.

This is true for all versions of Ruby. No version of Ruby has ever specified the existence of a GVL. And it is highly doubtful that any future version of Ruby will, either.