There's a deadlock in code in the PickAxe, and I'm not seein


#1

The following code (form pg. 739) deadlocks with a large count. What
am I missing?

Cheers

Dave

require ‘thwait’
require ‘sync’

class Counter
attr_reader :total_count
def initialize
@total_count = 0
@count_down = 0
@sync = Sync.new
end
def inc
@sync.synchronize(:EX) do
@total_count += 1
@count_down -= 1
end
end
def test_consistent
@sync.synchronize(:SH) do
fail “Bad counts” unless @total_count + @count_down == 0
end
end
end

count = Counter.new
waiter = ThreadsWait.new([])

create 10 threads that each inc() 10,000 times

10.times do
waiter.join_nowait(Thread.new { 100_000.times do
count.inc
count.test_consistent
end })
end

p waiter.all_waits
p count.total_count


#2

Dave T. wrote:

The following code (form pg. 739) deadlocks with a large count. What am
I missing?

Ok here, with ruby-1.8.4, Linux 2.6.12, Ubuntu. I tried 100 threads,
10_000 iterations, too.


#3

On Tue, 17 Jan 2006, Dave T. wrote:

The following code (form pg. 739) deadlocks with a large count. What am I
missing?

works for me on mac and linux. what are you on?

-a


#4

On 1/16/06, Dan H. removed_email_address@domain.invalid wrote:

Hummmm, no help here, works fine for me.

Ruby 1.8.2, RH-8…

Same for Ruby 1.8.3 on Ubuntu i486-linux.


#5

On Jan 16, 2006, at 4:41 PM, removed_email_address@domain.invalid wrote:

The following code (form pg. 739) deadlocks with a large count.
What am I missing?

works for me on mac and linux. what are you on?

OSX/ruby 1.8.2 (2004-12-30) [powerpc-darwin8.2.0]

dave[CVS/rubybook 19:52:46] ruby t.rb
deadlock 0x3a4e40: sleep:J(0x3b090c) - /Users/dave/ruby1.8/lib/ruby/
1.8/thwait.rb:121
deadlock 0x3b090c: sleep:- - /Users/dave/ruby1.8/lib/ruby/1.8/
sync.rb:150

deadlock 0x1b4af4: sleep:- - /Users/dave/ruby1.8/lib/ruby/1.8/
sync.rb:150
deadlock 0x1d5790: sleep:- (main) - /Users/dave/ruby1.8/lib/ruby/1.8/
thread.rb:281
/Users/dave/ruby1.8/lib/ruby/1.8/thwait.rb:119:in pop': Thread (0x3ca744): deadlock (fatal) from /Users/dave/ruby1.8/lib/ruby/1.8/thwait.rb:139:innext_wait’
from /Users/dave/ruby1.8/lib/ruby/1.8/thwait.rb:154:in
`all_waits’
from t.rb:35

It doesn’t always do it, but with 100,000 iterations, it does it most
of the time.

Interestingly, it doesn’t seem to do it with the precompiled Ruby.
I’m wondering if I build my local version with the wrong threading
options: the Apple build has --enable-pthread, and mine doesn’t

Anyone know if that would cause a problem?

Dave


#6

Hummmm, no help here, works fine for me.

Ruby 1.8.2, RH-8…

pridith:[2006.01.16-15:54]:time ./threads.rb
nil
1000000
32.200u 0.013x 0:32.59 99.1% 0+0k 0+0io 231pf+0w
pridith:[2006.01.16-15:56]:

-dwh-

On Mon, 2006-01-16 at 15:33, Dave T. wrote:

def inc
end
end

p waiter.all_waits
p count.total_count


I not only live each endless day in grief, but live each day
thinking about living each day in grief.
– C.S. Lewis

Daniel W. Hinz Xerox Corp: XOG/SEBU/MCD/EIDC/ISM&D
MS: 111-03J e-mail: removed_email_address@domain.invalid
800 Phillips Road TEL: 585.422.8078
Webster, NY 14580


#7

On 2006.01.17 11:09, Dave T. wrote:

Indeed, rebuilding my local Ruby with --enable-pthread fixes it. Is
this a bug in threading?

It seems to work OK here both ways. OSX threading, perhaps?

ruerue@yawn$ ruby -v
ruby 1.8.4 (2005-12-24) [amd64-freebsd6]

Dave

E


#8

On Jan 16, 2006, at 8:02 PM, Dave T. wrote:

Interestingly, it doesn’t seem to do it with the precompiled Ruby.
I’m wondering if I build my local version with the wrong threading
options: the Apple build has --enable-pthread, and mine doesn’t

Anyone know if that would cause a problem?

Indeed, rebuilding my local Ruby with --enable-pthread fixes it. Is
this a bug in threading?

Dave


#9

On Tue, 17 Jan 2006, Dave T. wrote:

The following code (form pg. 739) deadlocks with a large count. What
am I
missing?

Works on Ruby 1.8.2, WinXP.

jf