I want to pack a rack web-application in order to distribute it, In which a infinite loop resides. So it won't stop until my ctrl-c. But it seems ocra will only pack it when it ends 'naturally', and ctrl-c stopped the process.
have been tring use exit or abort in callmethod of object being passed to rake. after which the whole process do not end, some trace info appears though.
it is possible to invoke rake.run in a thread, and end application after given time. But I do not want to distribute a suicide version. so is there some more eligible and controllable way to normally end it ?
not sure if this is a insane question, but thanks in advance.
According to the OCRA docu, OCRA sets an environment variable OCRA_EXECUTABLE when being run.
So you could check for that environment var in your code and break the loop if OCRA is running, e.g.:
while true
break if ENV.has_key? 'OCRA_EXECUTABLE'
...
end
Related
Whenever I drop a debugging breakpoint with byebug, I am noticing inconsistencies with the text that I type. For instance, I am able to type the first 2-3 characters. However, after the first 2-3 characters, the terminal starts adding random square brackets and other characters. For instance when I type env, Byebug outputs: eenv, or when I try to access a key in env Byebug outputs something even worse: ^[[Aenv['QUERY_STRING'']^[[.
Has anyone ran into this problem with Byebug?
A similar issue occurred to me while working in ruby on rails, using multiple workers. I am making the assumption here that OP is using rails because env and query strings are mentioned in the output.
So, if you are running multiple workers while debugging, they can cause this sort of behaviour, because code is still being executed after the byebug breakpoint is hit, and more importantly: while you try to type letters in the terminal, causing input to get jumbled. Debugging middleware can exacerbate this behaviour, since middleware is always hit, causing this issue to happen only while debugging certain components but not for an example controllers.
Ensure that only one worker is hitting your breakpoint at a time. This could be done by setting your development environment to never run more than 1 worker at least for the time being
This is a parallelization issue. Either with multiple workers while running rails server, OR in my case it was:
class ActiveSupport::TestCase
# Run tests in parallel with specified workers
parallelize(workers: :number_of_processors) # <--- this is a madness freaking root
end
byebug (and any bb-based gem) terminal input going nuts after hitting a break point in this case
Working with ruby 1.9.3 with tk and I've found that I can't do a fork inside the mainloop that calls "exit" - I need to get out of the fork by doing something like exec().
Example program:
#!/usr/bin/ruby
require 'tk'
root = TkRoot.new
def doit
unless fork
puts "Inside the fork"
exit # This is where it falls apart
end
end
TkButton.new(root) {
text 'go'
command proc { doit }
}.pack
Tk.mainloop()
Press the button and we properly fork, but when fork calls 'exit' then we get:
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
ruby: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
ruby: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
I've discovered that I can hack a workaround by using something like "exec('echo')" instead of the exit, but that's just plain silly. What's going on that exit doesn't work? Is there some way to call XInitThreads from ruby (this isn't jruby or fxruby) that I can use and will that help?
From my research so far, it seems that ruby and Tk are pretty broken the moment you introduce threads or forking, but I have not been able to find a clean way to deal with this problem.
This problem exists with any Tcl built with thread support.
You will have to restructure your program so that the Tcl/Tk processes are separate entities and do not get forked.
The gui will need to send any input commands to the appropriate ruby thread and the threads will need to send data to the gui to be displayed.
I have a script named program.rb and would like to write a script named main.rb that would do the following:
system("ruby", "program.rb")
constantly check if program.rb is running until it is done
if program.rb has reached completion
exit main.rb
end
otherwise keep doing this until program.rb reaches completion{
if program.rb is not running and stopped before completing
restart program.rb from where it left off
end}
I've looked into Pidify but could not find a way to apply it to fit this exactly the right way...
Any help in how to approach this script would be greatly appreciated!
Update:
I could figure out how to resume running the script from where it left off in program.rb if there's no way to do it in main.rb
It's impossible to "restart script from where it left off" without full cooperation from the program.rb. That is, it should be able to advertise its progress (by writing current state to a file, maybe?) and be able to start correctly from a step specified in ARGV. There's no external ruby magic that can replace this functionality.
Also, if a program terminated abnormally, it means one of two things:
the error is (semi-)permanent (disk is full, no appropriate access rights to a file, etc). In this case, simply restarting the program would cause it to fail again. And again. Infinite fail loop.
the error is temporary (shaky internet connection). In this case, program should do better job with exception handling and retry on its own (instead of terminating).
In either case, there's no need for restarting, IMHO.
Well, here is one way.
Modify program.rb to take an optional flag argument --restart or something.
When program.rb starts up without this argument it will initialize a file to record its current state. Periodically, it will write whatever it needs into this file to record some kind of checkpoint.
When program.rb starts up with the restart flag, it will read its checkpoint file and start processing at that point. For this to work, it must either checkpoint all state changes or arrange for all processing between checkpoints to be idempotent so it can be repeated without ill effect.
There are lots of ways to monitor the health of program.rb. The best way is with some sort of ping, perhaps something like GET /health_check or a dummy message via a socket or pipe. You could just have a locked file to detect if the lock is still held, or you could record the PID on startup and check that it still exists.
So let's say pretty often a script runs that opens a browser and does web things:
require 'watir-webdriver'
$browser = Watir::Browser.new(:firefox, :profile => "botmode")
=> #<Watir::Browser:0x7fc97b06f558 url="about:blank" title="about:blank">
It could end gracefully with a browser.close, or it could crash sooner and leave behind the memory-hungry Firefox process, unnoticed until they accumulate and slow the server to a crawl.
My question is twofold:
What is a good practice to ensure that even in case of script failure anywhere leading to immediate error exit, the subprocess will always get cleaned up (I already have lots of short begin-rescue-end blocks peppered for other unrelated small tests)
More importantly, can I simply remember this Watir::Browser:0x7fc97b06f558 object address or PID somehow and re-assign it to another $browser variable in a whole new Ruby process, for example irb? I.e. can an orphaned browser on webdriver be re-attached later in another program using watir-webdriver on the same machine? From irb I could then get in and re-attach to the browser left behind by the crashed Ruby script, to examine the website it was on, check what went wrong, what elements are different than expected, etc.
Another hugely advantageous use of the latter would be to avoid the overhead of potentially hundreds of browser startups and shutdowns per day...best to keep one alive as sort of a daemon. The first run would attempt to reuse a previous browser object using my specially prepared botmode profile, otherwise create one. Then I would deliberately not call $browser.close at the end of my script. If nothing else I run an at job to kill the Xvfb :99 display FF runs inside of at the end of the day anyway (giving FF no choice but to die with it, if still running). Yes I am aware of Selenium standalone jar, but trying to avoid that java service footprint too.
Apologies if this is more a basic Ruby question. I just wasn't sure how to phrase it and keep getting irrelevant search results.
I guess, U cant just remember the variable from another process. But the solution might be creating a master process and process your script in loop in thread, periodically checking the browser running state. I'm using some thing similar in my acceptance tests on Cucumber + watir. So it will be some thing like that:
require 'rubygems'
require 'firewatir' # or watir
#browser = FireWatir::Firefox.new
t = Thread.new do
#browser.goto "http://google.com"
#call more browser actions here
end
while not_exit?
if t.stop?
# error occurred in thread, restart or exit
end
if browser_live?
# browser was killed for a some reason
# restart or exit
end
end
#browser.close
not_exit? - can be over TRAP for the ctrl+C
browser_live? - you can check if firefox browser running with processes listings
It is quite tricky but might work for you
You can use DRb like this:
browsers pool:
require 'drb'
require 'watir'
browser = Watir::Browser.new :chrome
DRb.start_service 'druby://127.0.0.1:9395', browser
gets
and then from test script use this browser:
require 'drb'
browser = DRbObject.new_with_uri 'druby://127.0.0.1:9395'
browser.goto 'stackoverflow.com'
I'm pretty sure that at the point ruby exits, any handles or pointers to something like a browser object would become invalid. So re-using something in a later ruby process is likely not a good approach. In addition I might be wrong on this, but it does seem that webdriver is not very good at connecting to a running browser process. So for your approach to work it would really all need to be wrapped by some master process that was calling all the tests etc.. and hey wait a sec, that's starting to sound like a framework, which you might already (or perhaps should be) using in the first place.
So a better solution is probably to look at whatever framework you are using to run your tests and investigate any capability for 'setup/teardown' actions (which can go by different names) which are run before and after either each test, groups of tests, or all tests. Going this way is good since most frameworks are designed to allow you to run any single test, or set of tests that you want to. And if your tests are well designed they can be run singly without having to expect the system was left in some perfect state by a prior test. Thus these sorts of setup/teardown actions are designed to work that way as well.
As an example Cucumber has this at the feature level, with the idea of a 'background' which is basically intended as a way to dry out scenarios by defining common steps to run before each scenario in a feature file. (such as navigating to and logging into your site) This could include a call to a series of steps that would look to see if a browser object existed, and if not create one. However you'd need to put that in every feature file which starts to become rather non dry.
Fortunately cucumber also allows a way to do this in one place via the use of Hooks. You can define hooks to run before steps, in the event of specific conditions, 'before' and 'after' each scenario, as well as code that runs once before any scenarios, and code defined to run 'at_exit' where you could close the browser after all scenarios have run.
If I was using cucumber I'd look at the idea of a some code in env.rb that would run at the start to create a browser, complemented by at_exit code to close the browser. Then perhaps also code in a before hook which could check to see that the browser is still there and re-create it if needed, and maybe logout actions in a after hook. Leave stuff like logging in for the individual scenarios, or a background block if all scenarios in a feature login with the same sort of user.
Not so much a solution but a workaround for part 1 of my question, using pkill. Posting here since it turned out to be a lot less trivial than I had hoped.
After the ruby script exits, its spawned processes (which may not at all belong in the same PID tree anymore, like firefox-bin) have a predictable "session leader" which turned out to be the parent of the bash shell calling rubyprogram.rb in my case. Available as $PPID in Bash, for when you have to go higher than $$.
Thus to really clean up unwanted heavyweight processes eg. after a ruby crash:
#!/bin/bash
# This is the script that wraps on top of Ruby scripts
./ruby_program_using_watirwebdriver_browser.rb myparams & # spawn ruby in background but keep going below:
sleep 11 # give Ruby a chance to launch its web browser
pstree -panu $$ # prints out a process tree starting under Bash, the parent of Ruby. Firefox may not show!
wait # now wait for Ruby to exit or crash
pkill -s $PPID firefox-bin # should only kill firefox-bin's caused above, not elsewhere on the system
# Another way without pkill, will also print out what's getting killed if anything:
awk '$7=="firefox-bin" && $3=="'$PPID'" {print $1}' <(ps x -o pid,pgid,sess,ppid,tty,time,comm) | xargs -rt kill
OPTIONAL
And since I use a dedicated Xvfb Xwindows server just for webdriving on DISPLAY :99, I can also count on xkill:
timeout 1s xwininfo -display :99 -root -all |awk '/("Navigator" "Firefox")/ {print $1}' |xargs -rt xkill -display :99 -id
# the timeout is in case xkill decides to wait for user action, when window id was missing
Just an update on part 2 of my question.
It seems one CAN serialize a Watir:Browser object with YAML, and because it's text-based the contents were quite interesting to me (e.g. some things I've only dreamed of tweaking hidden inside private elements of private classes...but that's a separate topic)
Deserializing from YAML is still trouble. While I haven't tested beyond the first try it gives me some kind of reg exp parse error...not sure what that's about.
(more on that at at how to serialize an object using TCPServer inside? )
Meanwhile, even attempting to serialize with Marshal, which is also built-in to Ruby but stores in binary format, results in a very reasonable-sounding error about not being able to dump a TCPServer object (apparently contained within my Watir:Browser pointed to by $browser)
All in all I'm not surprised at these results, but still pretty confident there is a way, until Watir arrives at something more native (like PersistentWebdriver or how it used to be in the days of jssh when you could simply attach to an already running browser with the right extension)
Until then, if serialization + deserialization to a working object gets too thorny I'll resort to daemonizing a portion of my Ruby to keep objects persistent and spare the frequent and costly setup/teardowns. And I did take a gander at some established (unit testing) frameworks but none seem to fit well yet within my overall software structure--I'm not web testing after all.
I want to limit the subprocesses count to 3. Once it hits 3 i wait until one of the processes stops and then execute a new one. I'm using Kernel.fork to start the process.
How do i get the number of running subprocesses? or is there a better way to do this?
A good question, but I don't think there's such a method in Ruby, at least not in the standard library. There's lots of gems out there....
This problem though sounds like a job for the Mutex class. Look up the section Condition Variables here on how to use Ruby's mutexes.
I usually have a Queue of tasks to be done, and then have a couple of threads consuming tasks until they receive an item indicating the end of work. There's an example in "Programming Ruby" under the Thread library. (I'm not sure if I should copy and paste the example to Stack Overflow - sorry)
My solution was to use trap("CLD"), to trap SIGCLD whenever a child process ended and decrease the counter (a global variable) of processes running.