This fixes an occasional [ASYNC BUG] failure in bootstraptest/test_fork.rb '[ruby-dev:37934]' which tests fork/pthread_create failure by setting RLIMIT_NPROC to 1 and triggering EAGAIN on pthread_create when attempting to recreate the timer thread.
The checks in rb_thread_wakeup_timer_thread_low only tried to guarantee proper ordering with native_stop_timer_thread, not rb_thread_create_timer_thread :x
Now, this should allow rb_thread_create_timer_thread to synchronize properly with rb_thread_wakeup_timer_thread_low by delaying the validation marking of the timer_thread_pipe until we are certain the timer thread is alive.
In this version, rb_thread_wakeup_timer_thread_low becomes a noop. Threading is still completely broken with NPROC==1, but there's not much we can do about it beside warn the user. We no longer spew a scary [ASYNC BUG] message or dump core on them.
thread_pthread.c (rb_thread_create_timer_thread): fix race
This fixes an occasional [ASYNC BUG] failure in
bootstraptest/test_fork.rb '[ruby-dev:37934]'
which tests fork/pthread_create failure by setting
RLIMIT_NPROC to 1 and triggering EAGAIN on pthread_create
when attempting to recreate the timer thread.
The problem timeline is as follows:
thread 1 thread 2¶
rb_thread_create_timer_thread
setup_communication_pipe
rb_thread_wakeup_timer_thread_low
pthread_create fails pipe looks valid, write!
CLOSE_INVALIDATE (x4) EBADF -> ASYNC BUG
The checks in rb_thread_wakeup_timer_thread_low only tried to
guarantee proper ordering with native_stop_timer_thread, not
rb_thread_create_timer_thread :x
Now, this should allow rb_thread_create_timer_thread to
synchronize properly with rb_thread_wakeup_timer_thread_low by
delaying the validation marking of the timer_thread_pipe until
we are certain the timer thread is alive.
In this version, rb_thread_wakeup_timer_thread_low becomes a
noop. Threading is still completely broken with NPROC==1, but
there's not much we can do about it beside warn the user.
We no longer spew a scary [ASYNC BUG] message or dump core
on them.
(rb_thread_create_timer_thread): until thread creation succeeds
[ruby-core:72590] [Bug #11922]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53373 b2dd03c8-39d4-4d8f-98ff-823fe69b080e