Hello
I do not understand the internals of Ruby IO but what I get here looks
really awful.
I am interfacing an application that processes lines of text and
buffers part of the output until EOF (or EOF tag). I thought using an
additional thread would be the right thing to do in this case: one
thread writes stuff, and as the application starts to output stuff
another thread wakes up to read it.
There are two problems here:
-
only reading inside the separate thread is possible, writing causes
stdin to be read into the program -
reading inside the thread produces deadlocks
Attaching the files required to reproduce both failures.
=================== mock.rb ===================
buf=[]
while l=gets
buf << l
puts buf.shift if buf.length >3
end
=================== garbage ===================
ilks nvd
sdh v
df bhl
dj fbo
fj wr;oug
rbfg
=================== testt.rb ===================
def unidentified l
false
end
def try_analyze *words
return [] if words.length < 1
analyzer = IO.popen( ‘ruby -w mock.rb’, IO::RDWR | IO::SYNC )
res = []
t = Thread.new( (IO::for_fd analyzer.fileno) ,res){|fd,ary|
while l = fd.gets do
break if l =~ %r|^$|
if l =~ /^$/
STDERR << “try_analyze: Empty line in output! \n”
next
else
ary.push l
end
end
fd.close rescue nil # hopefully prevents zombie hordes
}
words.each{|w|
STDERR.puts “try_analyze: #{w}”
analyzer.puts “”+w
}
analyzer.puts “”
analyzer.close_write
t.join
res.map{|w|
if unidentified w then
nil
else if w !~ /^<f/
STDERR << “try_analyze: JUNK: #{w} \n”
nil
else
w
end end
}
end
1.upto(10000){|_|
try_analyze *%w(a b c d e f g h i)
}
=================== testt2.rb ===================
def unidentified l
false
end
def try_analyze *words
return [] if words.length < 1
analyzer = IO.popen ‘ruby -w mock.rb’
res = []
t = Thread.new( (IO::for_fd analyzer.fileno) ,words){|fd,ary|
fd.sync = true
ary.each{|w|
STDERR.puts “try_analyze: #{w}”
fd.puts “”+w
}
fd.puts “”
analyzer.close_write
}
analyzer.sync = true
while l = analyzer.gets do
break if l =~ %r|^$|
if l =~ /^$/
STDERR << “try_analyze: Empty line in output! \n”
next
else
res.push l
end
end
fd.close rescue nil # hopefully prevents zombie hordes
res.map{|w|
if unidentified w then
nil
else if w !~ /^<f/
STDERR << “try_analyze: JUNK: #{w} \n”
nil
else
w
end end
}
end
1.upto(10){|_|
try_analyze *%w(a b c d e f g h i)
}
Use:
$ cat garbage | ruby -w testt2.rb
testt2.rb:47: warning: `*’ interpreted as argument prefix
try_analyze: a
try_analyze: JUNK: ilks nvd
try_analyze: JUNK: sdh v
try_analyze: JUNK: df bhl
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
try_analyze: a
$ cat garbage | ruby -w testt.rb
[lots of output snipped]
deadlock 0x53d4: sleep:F(4) - testt.rb:14
deadlock 0x31704: sleep:S (main) - testt.rb:27
testt.rb:27:in write': Thread(0x31704): deadlock (fatal) from testt.rb:27:inputs’
from testt.rb:27:in try_analyze' from testt.rb:25:ineach’
from testt.rb:25:in try_analyze' from testt.rb:45 from testt.rb:44:inupto’
from testt.rb:44
Thanks
Michal
