[ruby-core:37215] Re: [Request for Comment] avoid timer thread

SASADA Koichi <[e-mail]> wrote:
> (2011/06/14 3:37), Eric Wong wrote:
> > I'll just wait on the 1.9.3 version for now based on ko1's response \o/
> 
> Here is my current patch.  This is only tested on Linux on VirtualBox.
> I'm happy if you test on the other environment.
> 
> http://www.atdot.net/sp/view/yonwml/readonly
> http://www.atdot.net/sp/raw/yonwml

In case there are C extensions or FFI wrappers that fork() directly
without using Ruby, I prefer pthread_atfork() to close the pipe:

http://bogomips.org/ruby.git/commit/?h=sleepy-timer-thread&id=b8bb000953b

From b8bb000953b0c9d892bd9314054b80a3fe2eec48 Mon Sep 17 00:00:00 2001
From: Eric Wong <[e-mail]>
Date: Fri, 17 Jun 2011 17:50:32 -0700
Subject: [PATCH] thread_pthread.c: avoid pipe leak to extensions that fork()
 internally

Some extensions (or FFI wrapper) may call fork() directly and
bypass Ruby-specific hooks for fork().
---
 thread_pthread.c |   25 +++++++++++++++++++------
 1 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/thread_pthread.c b/thread_pthread.c
index c2771ac..5f61df4 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1085,14 +1085,32 @@ thread_timer(void *p)
     return NULL;
 }
 
+static void close_timer_thread_pipe(void)
+{
+    if (timer_thread_pipe[0] && close(timer_thread_pipe[0]) < 0) { rb_bug_errno("native_stop_timer_thread - close(ttp[0])", errno); }
+    if (timer_thread_pipe[1] && close(timer_thread_pipe[1]) < 0) { rb_bug_errno("native_stop_timer_thread - close(ttp[1])", errno); }
+    timer_thread_pipe[0] = timer_thread_pipe[1] = 0;
+}
+
 static void
 rb_thread_create_timer_thread(void)
 {
+    static int atfork_installed;
+    int err;
+
+    if (!atfork_installed) {
+	err = pthread_atfork(NULL, NULL, close_timer_thread_pipe);
+	if (err != 0) {
+	    fprintf(stderr, "[FATAL] Failed to install atfork hook for timer thread pipe (errno: %d)\n", err);
+	    exit(EXIT_FAILURE);
+	}
+	atfork_installed = 1;
+    }
+
     rb_enable_interrupt();
 
     if (!timer_thread_id) {
 	pthread_attr_t attr;
-	int err;
 
 	pthread_attr_init(&attr);
 #ifdef PTHREAD_STACK_MIN
@@ -1151,11 +1169,6 @@ native_reset_timer_thread(void)
     if (TT_DEBUG)  fprintf(stderr, "reset timer thread\n");
     timer_thread_id = 0;
     timer_thread_pid = 0;
-
-    /* close */
-    if (timer_thread_pipe[0] && close(timer_thread_pipe[0]) < 0) { rb_bug_errno("native_stop_timer_thread - close(ttp[0])", errno); }
-    if (timer_thread_pipe[1] && close(timer_thread_pipe[1]) < 0) { rb_bug_errno("native_stop_timer_thread - close(ttp[1])", errno); }
-    timer_thread_pipe[0] = timer_thread_pipe[1] = 0;
 }
 
 #ifdef HAVE_SIGALTSTACK
-- 
Eric Wong