From: Steve Tuckner <stevetuckner@...>
Date: 2004-02-22T04:28:22+09:00
Subject: Re: threads and blocking

Joel VanderWerf wrote:

> Shashank Date wrote:
>
>> It may have to do with the threads get scheduled to run. For example, 
>> this will block like you expected:
>>  
>> ruby -e "Thread.new{gets}; Thread.new{sleep(0.01);select nil}; 
>> Thread.new{puts 42}"
>
>
> Doesn't block in ruby 1.9.0 (2004-02-15) [i686-linux]. Maybe a windows 
> effect? My (limited) understanding of ruby threads is that thread 
> waiting on IO will not block the app.
>
> Also, a thread calling system will not block the app, as in
>
>   Thread.new {system "sleep 10"}
>
> However, flock does block the process.
>
>
On windows sockets will not generally block Ruby, but if you try a 
TCP#connect on a non-existant IP address, then all of Ruby will block 
for about 20 seconds. I think that this is a result of a poor windows 
non-blocking socket implementation. One solution that I have thought of 
but not tried, would be to use blocking sockets on windows and do the 
operation within a native thread and then just signal back to the ruby 
thread when there is a result of the operation.

Steve Tuckner