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Bug #9447
closedBad interaction between Fibers and Trap handlers in Ruby > 2.0.0
Description
Hi there,
I've been using and Alarm class I created, which gives Ruby code access to the alarm system call.
It used to work perfectly on 1.9.3 with no issues and more than 1 year of production usage.
Ruby 2.0.0 doesn't let me use it properly, apparently when there's an alarm timeout, the interpreter will think the code is in the trap context forever, so when I try to use Logger afterwards, it will fail (since it uses a Mutex internally).
Below is my Alarm implementation.
require 'dl'
require 'dl/import'
module Alarm
module SystemCall
extend DL::Importer
# imports the POSIX alarm function
begin
dlload 'libc.so.6'
rescue
begin
dlload 'libc.so.5'
rescue
dlload 'libc.dylib'
end
end
extern 'unsigned int alarm(unsigned int)'
end
def self.alarm(n)
# creates new fiber which will the code block passed as argument
fiber = Fiber.new { yield }
begin
# new signal handler for the alarm call
handler = Signal.trap('ALRM') do
# yields fiber, which makes the control flow continue after
# after the last resume call for this fiber
# (in other words, returns from this function)
Fiber.yield
end
# start timing
SystemCall.alarm(n)
# start running timed call
result = fiber.resume
ensure
# cancel alarms and restore the previous signal handler
SystemCall.alarm(0)
Signal.trap('ALRM', handler)
end
return result
end
end
Is this sort of thing really no longer supported in Ruby > 2.0.0 or is it a bug? As I've said, it worked perfectly on 1.9.3.
This class is used like this:
Alarm.alarm(timeout_seconds) do
# potentially time consuming operation which must have a timeout
end
Due to other requirements, I can't use the Timeout module, as it creates another thread.
Thanks in advance.
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