Bug #4681
closedTimeout.timeout doesn't actually time out?
Description
Documentation for Timeout says "A way of performing a potentially long-running operation in a thread, and terminating its execution if it hasn‘t finished by a fixed amount of time."
This doesn't actually seem to be what it does.
Example code:
#!/usr/bin/ruby
encoding: UTF-8¶
require 'open3'
require 'timeout'
puts "Time out after 2 seconds. Count them..."
result = Timeout.timeout(2) do
stdin, stdout, stderr = Open3.capture3("sleep 30")
output = stdout.read + "\n" + stderr.read
end
On my systems, this doesn't time out after 2 seconds. Instead, it runs for 30 seconds, and then throws an error saying it took longer than 2 seconds.
Updated by normalperson (Eric Wong) over 13 years ago
mathew murphy meta@pobox.com wrote:
This doesn't actually seem to be what it does.
Example code:
#!/usr/bin/ruby
encoding: UTF-8¶
require 'open3'
require 'timeout'puts "Time out after 2 seconds. Count them..."
result = Timeout.timeout(2) do
stdin, stdout, stderr = Open3.capture3("sleep 30")
output = stdout.read + "\n" + stderr.read
end
On my systems, this doesn't time out after 2 seconds. Instead, it runs
for 30 seconds, and then throws an error saying it took longer than 2
seconds.
It's because open3 has an ensure block where it does Thread#join and
that waits forever, so the timeout thread raised to unblock the
main thread, and then it got stuck again inside the ensure block.
diff --git a/lib/open3.rb b/lib/open3.rb
index b65cb19..d335f9f 100644
--- a/lib/open3.rb
+++ b/lib/open3.rb
@@ -207,6 +207,7 @@ module Open3
begin
return yield(*result)
ensure
-
parent_io.each{|io| io.close unless io.closed?}p [ :ensure, __FILE__, __LINE__ ]
wait_thr.join
end
@@ -702,6 +703,7 @@ module Open3
begin
return yield(*result)
ensure -
parent_io.each{|io| io.close unless io.closed?}p [ :ensure, __FILE__, __LINE__ ]
wait_thrs.each {|t| t.join }
end
You can work around it by having an extra timeout block (ugly):¶
puts "Time out after 2 seconds. Count them..."
Timeout.timeout(2) do
result = Timeout.timeout(2) do
stdin, stdout, stderr = Open3.capture3("sleep 30")
output = stdout.read + "\n" + stderr.read
end
end
But IMHO, timeout is a very fragile module and shouldn't be relied on.
--
Eric Wong
Updated by naruse (Yui NARUSE) about 13 years ago
- Status changed from Open to Assigned
- Assignee set to akr (Akira Tanaka)
Updated by nahi (Hiroshi Nakamura) about 13 years ago
- Target version set to 1.9.3
Updated by kosaki (Motohiro KOSAKI) about 13 years ago
- Status changed from Assigned to Rejected
I think Eric described the reason and workaround at commetn#1. IOW, it's spec unfortunately.
Updated by meta (mathew murphy) over 12 years ago
Just noting for the benefit of anyone else passing by that I posted a way to do popen3 with timeout at
https://gist.github.com/1032297