[ruby-cvs:70975] normal:r63884 (trunk): mjit: get rid of memory leak in pause+resume loop

[normal at ruby-lang.org]

normal	2018-07-08 16:27:24 +0900 (Sun, 08 Jul 2018)

  New Revision: 63884

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=63884

  Log:
    mjit: get rid of memory leak in pause+resume loop
    
    pthread_atfork is not idempotent and repeatedly calling it
    causes it to register the same hook repeatedly; leading to
    unbound memory growth.
    
    Ruby already has a (confusing-named) internal API for to call
    in the forked child process: rb_thread_atfork
    Call the MJIT child_after_fork hook inside that to prevent
    unbound growth with the following loop:
    
        loop do
          RubyVM::MJIT.pause
          RubyVM::MJIT.resume
        end

  Modified files:
    trunk/mjit.c
    trunk/thread.c
    trunk/thread_pthread.c
    trunk/thread_win32.c