Feature #2012: Set event_flags on thread creation if hook exists

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: 2.0.0

[mark-moseley (Mark Moseley)]

=begin
In ruby-debug, when a user sets a breakpoint that ends up executed by a later-created thread, then nothing will happen.

The only solution that I have at this point is to always set RUBY_EVENT_VM for all living threads every time the hook proc is called. I've tried to optimize this and failed; the cost of figuring out accurately if there's a new thread is always greater than the brute-force method of just always forcing the flags to be updated.

I propose adding the following patch to the core:

Index: thread.c

--- thread.c (revision 24710)
+++ thread.c (working copy)
@@ -497,6 +497,9 @@
th->thgroup = GET_THREAD()->thgroup;

  native_mutex_initialize(&th->interrupt_lock);

• if (GET_VM()->event_hooks != NULL)

•    th->event_flags |= RUBY_EVENT_VM;
  

• /* kick thread */
  st_insert(th->vm->living_threads, thval, (st_data_t) th->thread_id);
  native_thread_create(th);

This passes all Ruby tests, and fixes the problem that I've outlined.
=end

[mame (Yusuke Endoh)]

=begin
Hi --

Sorry for very late response!

2009/8/30 Mark Moseley [e-mail]:

In ruby-debug, when a user sets a breakpoint that ends up executed by a later-created thread, then nothing will happen.

Confirmed.

 $ ./ruby.org -e '
 > set_trace_func(proc {|*a| p a })
 > Thread.new { puts "foo" }.join
 > '
 ["c-return", "-e", 2, :set_trace_func, #<Binding:0x824d10c>, Kernel]
 ["line", "-e", 3, nil, #<Binding:0x824cfe0>, nil]
 ["c-call", "-e", 3, :new, #<Binding:0x824cf04>, Thread]
 ["c-call", "-e", 3, :initialize, #<Binding:0x824ce00>, Thread]
 ["c-return", "-e", 3, :initialize, #<Binding:0x824ccfc>, Thread]
 foo
 ["c-return", "-e", 3, :new, #<Binding:0x824cc0c>, Thread]
 ["c-call", "-e", 3, :join, #<Binding:0x824cb30>, Thread]
 ["c-return", "-e", 3, :join, #<Binding:0x824ca54>, Thread]

("c-call" event to the method `puts' is not found)

This issue affects the coverage feature too. It fails to measure
coverage that is run in sub thread. [ruby-dev:39950]

I propose adding the following patch to the core:

Index: thread.c

--- thread.c (revision 24710)
+++ thread.c (working copy)
@@ -497,6 +497,9 @@
th->thgroup = GET_THREAD()->thgroup;

native_mutex_initialize(&th->interrupt_lock);

• if (GET_VM()->event_hooks != NULL)

•    th->event_flags |= RUBY_EVENT_VM;
  

• /* kick thread */
  st_insert(th->vm->living_threads, thval, (st_data_t) th->thread_id);
  native_thread_create(th);

Basically I agree with your patch. But it leaves event_flags true
even if all vm-level hooks are removed. How about this patch:

diff --git a/thread.c b/thread.c
index 0ba41c7..c082471 100644
--- a/thread.c
+++ b/thread.c
@@ -531,6 +531,9 @@ thread_create_core(VALUE thval, VALUE args, VALUE
(*fn)(ANYARGS))
th->thgroup = GET_THREAD()->thgroup;

  native_mutex_initialize(&th->interrupt_lock);

• if (GET_VM()->event_hooks != NULL)
• th->event_flags |= RUBY_EVENT_VM;
• /* kick thread */
  st_insert(th->vm->living_threads, thval, (st_data_t) th->thread_id);
  err = native_thread_create(th);
  @@ -3750,7 +3753,12 @@ rb_threadptr_exec_event_hooks(rb_thread_t *th,
  rb_event_flag_t flag, VALUE self,
  exec_event_hooks(th->event_hooks, flag, self, id, klass);
  }
  if (wait_event & RUBY_EVENT_VM) {

• exec_event_hooks(th->vm->event_hooks, flag, self, id, klass);

• if (th->vm->event_hooks == NULL) {

•  th->event_flags &= (~RUBY_EVENT_VM);
  

• }
• else {

•  exec_event_hooks(th->vm->event_hooks, flag, self, id, klass);
  

• }
  }
  th->errinfo = errinfo;
  }

--
Yusuke ENDOH [e-mail]

=end

[mame (Yusuke Endoh)]

• Category set to core
• Assignee set to ko1 (Koichi Sasada)

=begin

=end

[rogerdpack (Roger Pack)]

=begin
This patch seems to fix the threading difficulties for ruby-prof as well.

Koichi could you take a look at it sometime?

-r
=end

[mame (Yusuke Endoh)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

=begin
This issue was solved with changeset r27033.
Mark, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

=end

[mame (Yusuke Endoh)]

=begin
Hi,

2010/1/7 Yusuke ENDOH [e-mail]:

2009/8/30 Mark Moseley [e-mail]:

In ruby-debug, when a user sets a breakpoint that ends up executed by a later-created thread, then nothing will happen.

I've committed the patch I wrote ([ruby-core:27471]).

I believe that this is certainly a bug and my patch is benign,
but I'm happy to revert it if ko1 disagree.

--
Yusuke ENDOH [e-mail]

=end