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-rw-r--r--test/ruby/test_signal.rb20
-rw-r--r--thread_pthread.c42
2 files changed, 61 insertions, 1 deletions
diff --git a/test/ruby/test_signal.rb b/test/ruby/test_signal.rb
index b8a20d945c0..425dc26574c 100644
--- a/test/ruby/test_signal.rb
+++ b/test/ruby/test_signal.rb
@@ -369,4 +369,24 @@ class TestSignal < Test::Unit::TestCase
ensure
trap(:CHLD, old) if Signal.list['CHLD']
end
+
+ def test_sigwait_fd_unused
+ t = EnvUtil.apply_timeout_scale(0.1)
+ assert_separately([], <<-End)
+ tgt = $$
+ trap(:TERM) { exit(0) }
+ e = "Process.daemon; sleep #{t * 2}; Process.kill(:TERM,\#{tgt})"
+ term = [ '#{EnvUtil.rubybin}', '--disable=gems', '-e', e ]
+ t2 = Thread.new { sleep } # grab sigwait_fd
+ Thread.pass until t2.stop?
+ Thread.new do
+ sleep #{t}
+ t2.kill
+ t2.join
+ end
+ Process.spawn(*term)
+ # last thread remaining, ensure it can react to SIGTERM
+ loop { sleep }
+ End
+ end if Process.respond_to?(:kill) && Process.respond_to?(:daemon)
end
diff --git a/thread_pthread.c b/thread_pthread.c
index 209ed6781cc..92ec66af1ec 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1911,7 +1911,7 @@ rb_sigwait_fd_get(const rb_thread_t *th)
return signal_self_pipe.normal[0];
}
}
- return -1; /* avoid thundering herd */
+ return -1; /* avoid thundering herd and work stealing/starvation */
}
void
@@ -1996,6 +1996,43 @@ rb_sigwait_sleep(rb_thread_t *th, int sigwait_fd, const struct timespec *ts)
}
}
+/*
+ * This function does not exclusively acquire sigwait_fd, so it
+ * cannot safely read from it. However, it can be woken up in
+ * 4 ways:
+ *
+ * 1) ubf_select (from another thread)
+ * 2) rb_thread_wakeup_timer_thread (from signal handler)
+ * 3) any unmasked signal hitting the process
+ * 4) periodic ubf timer wakeups (after 3)
+ */
+static void
+native_ppoll_sleep(rb_thread_t *th, rb_hrtime_t *rel)
+{
+ rb_native_mutex_lock(&th->interrupt_lock);
+ th->unblock.func = ubf_select;
+ th->unblock.arg = th;
+ rb_native_mutex_unlock(&th->interrupt_lock);
+
+ GVL_UNLOCK_BEGIN(th);
+ if (!RUBY_VM_INTERRUPTED(th->ec)) {
+ struct pollfd pfd;
+ struct timespec ts;
+
+ pfd.fd = signal_self_pipe.normal[0]; /* sigwait_fd */
+ pfd.events = POLLIN;
+ (void)ppoll(&pfd, 1, rb_hrtime2timespec(&ts, rel), 0);
+
+ /*
+ * do not read the fd, here, let uplevel callers or other threads
+ * that, otherwise we may steal and starve other threads
+ */
+ }
+ unblock_function_clear(th);
+ unregister_ubf_list(th);
+ GVL_UNLOCK_END(th);
+}
+
static void
native_sleep(rb_thread_t *th, rb_hrtime_t *rel)
{
@@ -2020,6 +2057,9 @@ native_sleep(rb_thread_t *th, rb_hrtime_t *rel)
rb_sigwait_fd_put(th, sigwait_fd);
rb_sigwait_fd_migrate(th->vm);
}
+ else if (th == th->vm->main_thread) { /* always able to handle signals */
+ native_ppoll_sleep(th, rel);
+ }
else {
native_cond_sleep(th, rel);
}