My ruby version is 1.9, running under Linux-2.6.31 kernel.
For the code above, though we know the @count isn't safe for sharing.
But the result is always correct.
So can we say ruby-1.9 behaves better on threads than 1.8?
My ruby version is 1.9, running under Linux-2.6.31 kernel.
For the code above, though we know the @count isn't safe for sharing.
But the result is always correct.
So can we say ruby-1.9 behaves better on threads than 1.8?
The test proves nothing other than that you got what seems like a proper sum in the end. The runtime could have made accesses to @count atomic - or you could have been lucky (more likely).
It's actually the other way round: if the result would have been != 20000 Ruby 1.9 could be said to behave better on threads than 1.8. The reason is that this would tell you that there are actually concurrent accesses to the same memory, which means there would be more concurrency in 1.9 than in 1.8 with its green threads.
A system which guards accesses to shared resources *without* explicit synchronization would be very bad because it would sacrifice performance without reason.
Kind regards
robert
···
On 12.03.2010 04:01, Jean G. wrote:
Hello,
$ cat count_threads.rb
class Counter
attr_reader :count
def initialize @count = 0
end
def tick @count += 1
end
end
My ruby version is 1.9, running under Linux-2.6.31 kernel.
For the code above, though we know the @count isn't safe for sharing.
But the result is always correct.
So can we say ruby-1.9 behaves better on threads than 1.8?
On 12 March 2010 18:03, Roger Pack <rogerpack2005@gmail.com> wrote:
> My ruby version is 1.9, running under Linux-2.6.31 kernel.
> For the code above, though we know the @count isn't safe for sharing.
> But the result is always correct.
> So can we say ruby-1.9 behaves better on threads than 1.8?
My suspicion is it has to do with the way threads work in 1.9. Read http://blog.urbylog.info/2010/01/inside-ruby-19-interpreter-threading-in.html\.
I suspect that the GVL is not released while executing the += operator,
making a real context switch impossible, therefore preventing the other
thread from even running while the assignment is taking place.
Of course you should NOT be counting on the GVL to synchronize your code.
···
On 3/13/2010 7:09 AM, Benoit Daloze wrote:
On 12 March 2010 18:03, Roger Pack <rogerpack2005@gmail.com> wrote:
My ruby version is 1.9, running under Linux-2.6.31 kernel.
For the code above, though we know the @count isn't safe for sharing.
But the result is always correct.
So can we say ruby-1.9 behaves better on threads than 1.8?
