Hi,
I'm getting a deadlock on this small program, on both Windows
and Linux:
···
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
require 'net/ftp'
Thread.abort_on_exception = true
ftp = Net::FTP.new('ftp.idsoftware.com')
p( Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}.value )
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# ruby -v ftp_safe_test.rb
ruby 1.8.4 (2005-12-24) [i386-mswin32]
ftp_safe_test.rb:4:in `value': Thread(0x27855c8): deadlock (fatal)
from ftp_safe_test.rb:4
$ ruby -v safe_ftp_test.rb
ruby 1.8.4 (2005-12-24) [i686-linux]
safe_ftp_test.rb:4:in `value': Thread(0x4f060748): deadlock (fatal)
from safe_ftp_test.rb:4
Now, I didn't necessarily expect the code to WORK at $SAFE=4,
but I was anticipating a SecurityError rather than a deadlock.
(I've tried it with Thread.abort_on_exception both true and
false, same result.)
Any thoughts?
Thanks,
Regards,
Bill
Hi Bill-
Hi,
I'm getting a deadlock on this small program, on both Windows
and Linux:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
require 'net/ftp'
Thread.abort_on_exception = true
ftp = Net::FTP.new('ftp.idsoftware.com')
p( Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}.value )
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# ruby -v ftp_safe_test.rb
ruby 1.8.4 (2005-12-24) [i386-mswin32]
ftp_safe_test.rb:4:in `value': Thread(0x27855c8): deadlock (fatal)
from ftp_safe_test.rb:4
$ ruby -v safe_ftp_test.rb
ruby 1.8.4 (2005-12-24) [i686-linux]
safe_ftp_test.rb:4:in `value': Thread(0x4f060748): deadlock (fatal)
from safe_ftp_test.rb:4
Now, I didn't necessarily expect the code to WORK at $SAFE=4,
but I was anticipating a SecurityError rather than a deadlock.
(I've tried it with Thread.abort_on_exception both true and
false, same result.)
Any thoughts?
Thanks,
Regards,
Bill
Are you using ruby 1.8.6 by chance? If so install the laets fastthread gem and require it in your script to see if it fixes the deadlock. Unfortunately the fastthread code in the ruby1.8.6 release has some bugs that are fixed in the fastthread gem
Cheers-
-- Ezra Zygmuntowicz-- Lead Rails Evangelist
-- ez@engineyard.com
-- Engine Yard, Serious Rails Hosting
-- (866) 518-YARD (9273)
···
On Apr 17, 2007, at 4:34 PM, Bill Kelly wrote:
Hi,
At Wed, 18 Apr 2007 08:34:03 +0900,
Bill Kelly wrote in [ruby-talk:248300]:
require 'net/ftp'
Thread.abort_on_exception = true
ftp = Net::FTP.new('ftp.idsoftware.com')
th = Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}
Thread.critical = false
p th.value
···
--
Nobu Nakada
Hi Ezra,
I'm getting a deadlock on this small program, on both Windows
and Linux:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
require 'net/ftp'
Thread.abort_on_exception = true
ftp = Net::FTP.new('ftp.idsoftware.com')
p( Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}.value )
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# ruby -v ftp_safe_test.rb
ruby 1.8.4 (2005-12-24) [i386-mswin32]
ftp_safe_test.rb:4:in `value': Thread(0x27855c8): deadlock (fatal)
from ftp_safe_test.rb:4
$ ruby -v safe_ftp_test.rb
ruby 1.8.4 (2005-12-24) [i686-linux]
safe_ftp_test.rb:4:in `value': Thread(0x4f060748): deadlock (fatal)
from safe_ftp_test.rb:4
Now, I didn't necessarily expect the code to WORK at $SAFE=4,
but I was anticipating a SecurityError rather than a deadlock.
(I've tried it with Thread.abort_on_exception both true and
false, same result.)
Are you using ruby 1.8.6 by chance? If so install the laets fastthread gem and require it in your script to see if it fixes the deadlock. Unfortunately the fastthread code in the ruby1.8.6 release has some bugs that are fixed in the fastthread gem
The above was 1.8.4 with the standard thread.rb.
Trying ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
...I still get the deadlock, with or without fastthread:
ruby -v ftp_safe_test.rb
ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
ftp_safe_test.rb:5:in `value': Thread(0x50df1704): deadlock (fatal)
from ftp_safe_test.rb:5
Regards,
Bill
>At Wed, 18 Apr 2007 08:34:03 +0900,
>Bill Kelly wrote in [ruby-talk:248300]:
>> require 'net/ftp'
>> Thread.abort_on_exception = true
>> ftp = Net::FTP.new('ftp.idsoftware.com')
> th = Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}
> Thread.critical = false
> p th.value
Who set Thread.critical? It should be fixed, I think.
It seems to be something called by ftp.login: (I added some
sleeps to coordinate the two threads.)
···
From: "Yukihiro Matsumoto" <matz@ruby-lang.org>
In message "Re: Why does this code deadlock?" > on Wed, 18 Apr 2007 16:21:48 +0900, Nobuyoshi Nakada <nobu@ruby-lang.org> writes:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
require 'fastthread'
require 'net/ftp'
Thread.abort_on_exception = true
puts "1. crit=#{Thread.critical}"
ftp = Net::FTP.new('ftp.idsoftware.com')
puts "2. crit=#{Thread.critical}"
th = Thread.new {sleep(2); $SAFE=4; sleep(2); ftp.login('anonymous', 'abc@def.com')}
puts "3. crit=#{Thread.critical}"
sleep(3)
puts "4. crit=#{Thread.critical}"
sleep(2)
puts "5. crit=#{Thread.critical}"
# Thread.critical = false
p th.value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ ruby -v ftp_safe_test.rb
ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
1. crit=false
2. crit=false
3. crit=false
4. crit=false
5. crit=true
ftp_safe_test.rb:14:in `value': Thread(0x525ad708): deadlock (fatal)
from ftp_safe_test.rb:14
If I uncomment the `Thread.critical = false', it prints:
$ ruby -v ftp_safe_test.rb
ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
1. crit=false
2. crit=false
3. crit=false
4. crit=false
5. crit=true
/opt/lib/ruby/1.8/monitor.rb:284:in `mon_acquire': Insecure: can't modify instance variable (SecurityError)
from ftp_safe_test.rb:14:in `value'
from ftp_safe_test.rb:14
This is in MonitorMixin::ConditionVariable:
def mon_acquire(queue)
while @mon_owner && @mon_owner != Thread.current
queue.push(Thread.current)
Thread.stop
Thread.critical = true
end
@mon_owner = Thread.current
end
It looks like several methods in that class may want
ensure blocks enforcing their final `Thread.critical = false'
statements? Such as mon_try_enter, mon_enter, mon_exit,
etc.
Regards,
Bill
Hi,
At Wed, 18 Apr 2007 16:53:25 +0900,
Yukihiro Matsumoto wrote in [ruby-talk:248325]:
>At Wed, 18 Apr 2007 08:34:03 +0900,
>Bill Kelly wrote in [ruby-talk:248300]:
>> require 'net/ftp'
>> Thread.abort_on_exception = true
>> ftp = Net::FTP.new('ftp.idsoftware.com')
> th = Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}
> Thread.critical = false
> p th.value
Who set Thread.critical? It should be fixed, I think.
mon_acquire called from mon_enter fails because of
SecurityError, and leaves Thread.critical true.
Index: lib/monitor.rb
···
===================================================================
--- lib/monitor.rb (revision 12191)
+++ lib/monitor.rb (working copy)
@@ -106,12 +106,15 @@ def wait(timeout = nil)
ensure
Thread.critical = true
- if timer && timer.alive?
- Thread.kill(timer)
+ begin
+ if timer && timer.alive?
+ Thread.kill(timer)
+ end
+ if @waiters.include?(Thread.current) # interrupted?
+ @waiters.delete(Thread.current)
+ end
+ @monitor.instance_eval {mon_enter_for_cond(count)}
+ ensure
+ Thread.critical = false
end
- if @waiters.include?(Thread.current) # interrupted?
- @waiters.delete(Thread.current)
- end
- @monitor.instance_eval {mon_enter_for_cond(count)}
- Thread.critical = false
end
end
@@ -211,4 +214,5 @@ def mon_enter
mon_acquire(@mon_entering_queue)
@mon_count += 1
+ ensure
Thread.critical = false
end
@@ -300,6 +304,7 @@ def mon_exit_for_cond
count = @mon_count
@mon_count = 0
- mon_release
return count
+ ensure
+ mon_release
end
end
--
Nobu Nakada
ftp.login calls synchronize in thread.rb, which calls lock in
thread.rb, which sets critical:
def lock
while (Thread.critical = true; @locked)
@waiting.push Thread.current
Thread.stop
end
@locked = true
Thread.critical = false
self
end
Maybe I'm barking up the wrong tree.
···
On 4/18/07, Bill Kelly <billk@cts.com> wrote:
From: "Yukihiro Matsumoto" <matz@ruby-lang.org>
>
> In message "Re: Why does this code deadlock?" > > on Wed, 18 Apr 2007 16:21:48 +0900, Nobuyoshi Nakada <nobu@ruby-lang.org> writes:
>
> >At Wed, 18 Apr 2007 08:34:03 +0900,
> >Bill Kelly wrote in [ruby-talk:248300]:
> >> require 'net/ftp'
> >> Thread.abort_on_exception = true
> >> ftp = Net::FTP.new('ftp.idsoftware.com')
> > th = Thread.new {$SAFE=4; ftp.login('anonymous', 'abc@def.com')}
> > Thread.critical = false
> > p th.value
>
> Who set Thread.critical? It should be fixed, I think.
It seems to be something called by ftp.login: (I added some
sleeps to coordinate the two threads.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
require 'fastthread'
require 'net/ftp'
Thread.abort_on_exception = true
puts "1. crit=#{Thread.critical}"
ftp = Net::FTP.new('ftp.idsoftware.com')
puts "2. crit=#{Thread.critical}"
th = Thread.new {sleep(2); $SAFE=4; sleep(2); ftp.login('anonymous', 'abc@def.com')}
puts "3. crit=#{Thread.critical}"
sleep(3)
puts "4. crit=#{Thread.critical}"
sleep(2)
puts "5. crit=#{Thread.critical}"
# Thread.critical = false
p th.value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ ruby -v ftp_safe_test.rb
ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
1. crit=false
2. crit=false
3. crit=false
4. crit=false
5. crit=true
ftp_safe_test.rb:14:in `value': Thread(0x525ad708): deadlock (fatal)
from ftp_safe_test.rb:14
If I uncomment the `Thread.critical = false', it prints:
$ ruby -v ftp_safe_test.rb
ruby 1.8.6 (2007-03-16 patchlevel 3) [i686-linux]
1. crit=false
2. crit=false
3. crit=false
4. crit=false
5. crit=true
/opt/lib/ruby/1.8/monitor.rb:284:in `mon_acquire': Insecure: can't modify instance variable (SecurityError)
from ftp_safe_test.rb:14:in `value'
from ftp_safe_test.rb:14
This is in MonitorMixin::ConditionVariable:
def mon_acquire(queue)
while @mon_owner && @mon_owner != Thread.current
queue.push(Thread.current)
Thread.stop
Thread.critical = true
end
@mon_owner = Thread.current
end
ftp.login calls synchronize in thread.rb, which calls lock in
thread.rb, which sets critical:
def lock
while (Thread.critical = true; @locked)
@waiting.push Thread.current
Thread.stop
end
@locked = true
Thread.critical = false
self
end
Hmm. Not shure if this has changed, but in the 1.8.6 sources,
net/ftp uses MonitorMixin:
require "monitor"
module Net
...
class FTP
include MonitorMixin
...
end
end
Tracing the execution with a set_trace_func shows
Net::FTP#login -> MonitorMixin#synchronize -> MonitorMixin#mon_enter
setting Thread.critical:
call /opt/lib/ruby/1.8/net/ftp.rb:371 login Net::FTP
line /opt/lib/ruby/1.8/net/ftp.rb:372 login Net::FTP
c-call /opt/lib/ruby/1.8/net/ftp.rb:372 == String
c-return /opt/lib/ruby/1.8/net/ftp.rb:372 == String
c-call /opt/lib/ruby/1.8/net/ftp.rb:372 == String
c-return /opt/lib/ruby/1.8/net/ftp.rb:372 == String
line /opt/lib/ruby/1.8/net/ftp.rb:376 login Net::FTP
line /opt/lib/ruby/1.8/net/ftp.rb:377 login Net::FTP
call /opt/lib/ruby/1.8/monitor.rb:235 synchronize MonitorMixin
line /opt/lib/ruby/1.8/monitor.rb:236 synchronize MonitorMixin
call /opt/lib/ruby/1.8/monitor.rb:209 mon_enter MonitorMixin
line /opt/lib/ruby/1.8/monitor.rb:210 mon_enter MonitorMixin
c-call /opt/lib/ruby/1.8/monitor.rb:210 critical= Thread
c-return /opt/lib/ruby/1.8/monitor.rb:210 critical= Thread
line /opt/lib/ruby/1.8/monitor.rb:211 mon_enter MonitorMixin
call /opt/lib/ruby/1.8/monitor.rb:278 mon_acquire MonitorMixin
line /opt/lib/ruby/1.8/monitor.rb:279 mon_acquire MonitorMixin
line /opt/lib/ruby/1.8/monitor.rb:284 mon_acquire MonitorMixin
c-call /opt/lib/ruby/1.8/monitor.rb:284 current Thread
c-return /opt/lib/ruby/1.8/monitor.rb:284 current Thread
c-call /opt/lib/ruby/1.8/monitor.rb:284 new Class
c-call /opt/lib/ruby/1.8/monitor.rb:284 initialize Exception
c-return /opt/lib/ruby/1.8/monitor.rb:284 initialize Exception
c-return /opt/lib/ruby/1.8/monitor.rb:284 new Class
c-call /opt/lib/ruby/1.8/monitor.rb:284 backtrace Exception
c-return /opt/lib/ruby/1.8/monitor.rb:284 backtrace Exception
c-call /opt/lib/ruby/1.8/monitor.rb:284 set_backtrace Exception
c-return /opt/lib/ruby/1.8/monitor.rb:284 set_backtrace Exception
raise /opt/lib/ruby/1.8/monitor.rb:284 mon_acquire MonitorMixin
return /opt/lib/ruby/1.8/monitor.rb:279 mon_acquire MonitorMixin
return /opt/lib/ruby/1.8/monitor.rb:210 mon_enter MonitorMixin
return /opt/lib/ruby/1.8/monitor.rb:236 synchronize MonitorMixin
return /opt/lib/ruby/1.8/net/ftp.rb:372 login Net::FTP
Regards,
Bill
···
From: "Leslie Viljoen" <leslieviljoen@gmail.com>
