Bug #6416
Deadlock when calling Thread#join from signal interrupt context
Description
=begin
The interpreter can deadlock when calling Thread#join both from the main context and from the signal handler context.
t = Thread.new{ sleep 3 }
Signal.trap "SIGINT" do
t.join
end
puts 'Press ctrl + c now'
t.join
The above will deadlock on linux x86_64 with ruby 1.9.x and ruby trunk. It works fine with ruby 1.8.7-p352 and JRuby.
=end
Associated revisions
- vm_core.h (rb_thread_struct): added 'in_trap' member for marking running trap handler.
- signal.c (signal_exec): turn on in_trap when running trap.
- thread.c (Init_Thread, thread_create_core): initialize in_trap when creating new threads.
- thread.c (thread_join_m): raise ThreadError when running trap handler.Bug [#6416]
- test/ruby/test_thread.rb (test_thread_join_in_trap): new test for the above.
- vm_core.h (rb_thread_struct): added 'in_trap' member for marking running trap handler.
- signal.c (signal_exec): turn on in_trap when running trap.
- thread.c (Init_Thread, thread_create_core): initialize in_trap when creating new threads.
- thread.c (thread_join_m): raise ThreadError when running trap handler.Bug [#6416]
- test/ruby/test_thread.rb (test_thread_join_in_trap): new test for the above.
- vm_core.h (rb_thread_struct): added 'in_trap' member for marking running trap handler.
- signal.c (signal_exec): turn on in_trap when running trap.
- thread.c (Init_Thread, thread_create_core): initialize in_trap when creating new threads.
- thread.c (thread_join_m): raise ThreadError when running trap handler.Bug [#6416]
- test/ruby/test_thread.rb (test_thread_join_in_trap): new test for the above.
- vm_core.h (rb_thread_struct): added 'in_trap' member for marking running trap handler.
- signal.c (signal_exec): turn on in_trap when running trap.
- thread.c (Init_Thread, thread_create_core): initialize in_trap when creating new threads.
- thread.c (thread_join_m): raise ThreadError when running trap handler.Bug [#6416]
- test/ruby/test_thread.rb (test_thread_join_in_trap): new test for the above.
History
#1
[ruby-core:45089]
Updated by mame (Yusuke Endoh) about 5 years ago
Updated by - Status changed from Open to Assigned
- Assignee set to kosaki (Motohiro KOSAKI)
Kosaki-san, could you take a look?
--
Yusuke Endoh mame@tsg.ne.jp
#2
[ruby-core:45123]
Updated by kosaki (Motohiro KOSAKI) about 5 years ago
Updated by - Assignee changed from kosaki (Motohiro KOSAKI) to ko1 (Koichi Sasada)
Hi ko1,
This is because thread_join() is not designed reentrant. It can insert a thread twice join_list. And then, join_list
is going to become circular ring and it lead to deadlock.
So, I think th.join in trap context should raise ThreadError. What do you think?
#3
[ruby-core:48572]
Updated by ko1 (Koichi Sasada) over 4 years ago
Updated by - Target version set to 2.0.0
Please give me a time.
#4
[ruby-core:50134]
Updated by ko1 (Koichi Sasada) over 4 years ago
- Assignee changed from ko1 (Koichi Sasada) to kosaki (Motohiro KOSAKI)
I agree with kosaki-san's comment.
#5
[ruby-core:50157]
Updated by kosaki (Motohiro KOSAKI) over 4 years ago
- Status changed from Assigned to Closed
Fixed at r37852.
Thanks, Timothy!
#6
[ruby-core:50239]
Updated by authorNari (Narihiro Nakamura) over 4 years ago
Updated by Hello
I need sometimes to call Thread#join in Signal.trap when I want to implement safe termination in a server.
For instance: https://gist.github.com/4158509
Is it a wrong use case in the first place?
Thanks.
#7
[ruby-core:50240]
Updated by kosaki (Motohiro KOSAKI) over 4 years ago
Nari,
In your case, main thread and trap handler uses the same mutex and it is racy and deadlockable. Even if I revert my change, it wouldn't work.
#8
[ruby-core:50242]
Updated by authorNari (Narihiro Nakamura) over 4 years ago
kosaki (Motohiro KOSAKI) wrote:
Nari,
In your case, main thread and trap handler uses the same mutex and it is racy and deadlockable. Even if I revert my change, it wouldn't work.
I see, Thanks!