Okay, I am an idiot. I had the "directory watch" setup to watch the
directory where the uberjar was built, so of course it was triggered
thousands of time while the uberjar was built, since I guess every new byte
added to the uberjar triggers the change event.
So I set my app to listen on the final directory, where the final uberjar
is moved, just once, when the uberjar is complete, and now the app behaves
the way I was expecting it to.
On Sunday, August 9, 2015 at 1:13:56 PM UTC-4, Lawrence Krubner wrote:
>
>
> Let's assume for a moment that, for some strange reason, the "directory
> watching" strategy won't work here. Does anyone have any other suggestions?
> I am thinking there must be a simple way to setup Jenkins and Supervisord
> to run these apps, but what I'm doing keeps getting more and more complex,
> which is typically a warning sign that I'm on the wrong track.
>
>
>
>
> On Saturday, August 8, 2015 at 5:24:28 PM UTC-4, Lawrence Krubner wrote:
>>
>> I feel stupid, but I have not been able to track this down.
>>
>> The background is that I have Jenkins running on the server, and when
>> triggered it pulls code from Github, compiles it, and then moves the final
>> uberjar to the directory where I keep all the uberjars that run on this
>> server. Then I have an app that should kill all currently running
>> instances. Then Supervisord should step in and restart the instances, using
>> the new uberjars for the new instances.
>>
>> All of this works, but I have been doing one bit by hand: "kill all
>> currently running instances". I log in as root and run a script that kills
>> the old instances. But just today I wrote a quick Clojure app to automate
>> this for me (the whole app is 50 lines of code, so this is a very small
>> app).
>>
>> To trigger the main action, I thought the app should set a watcher on the
>> final directory where Jenkins moves the uberjars to. When Jenkins moves a
>> new uberjar to the directory, the watch would be triggered and then it
>> could run the "kill all currently running instances" script. However, I
>> assumed that the ""kill all currently running instances"" script would be
>> triggered once each time the uberjar was updated, but instead it seems to
>> be triggered infinitely. Does a JVM app, or a Clojure app, change the dir
>> its in, on launch? Or is the problem in my own code? I'm using Chris
>> Zheng's excellent Hara library for the Watch. This is the main function of
>> my app, which is called on startup:
>>
>> (defn establish-watchers []
>> "The config contains a hashmap which has a 'watchers' key, which
>> contains a vector that holds hashmaps with 2 keys, one pointing to the
>> directory that should be watched and the other pointing to the command that
>> should be run when the watch is triggered."
>> (let [config (read-string (slurp "/etc/fiit.edn"))
>> watchers (:watchers config)]
>> (doseq [w watchers]
>> (common-watch/add (clojure.java.io/file (:dir-to-watch w)) (keyword
>> (:dir-to-watch w))
>> (fn [f k _ [cmd file]]
>> (pprint/pprint (:out (sh/sh (:action-to-do w)))))
>> {:types #{:create :modify}
>> :recursive false
>> :async false}))))
>>
>> So if I log in as root and start the app like this:
>>
>> /usr/bin/java -jar /home/jenkins/fiit/fiit-1-standalone.jar
>>
>> Then at the terminal I see this, which I expect:
>>
>> [/home/jenkins/sarr]
>> [/home/jenkins/food_for_all]
>>
>> Those are the 2 directories that it is watching.
>>
>> Then if I trigger Jenkins for the sarr app, Jenkins will pull the sarr
>> code from Github, rebuild the sarr uberjar, and move the uberjar to
>> /home/jenkins/sarr.
>>
>> All of that works just great. And then my app sees there has been a
>> change in /home/jenkins/sarr, and so it calls the command to kill all
>> existing instances of the sarr app. However, instead of doing this once, it
>> starts doing so an infinite number of times. At the terminal I see:
>>
>> (sarr is a Java app, not a Clojure app)
>>
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \nroot 25593 0.0 0.1 5813460 19452 ?
>> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\nroot 25595 0.0 0.1 5813460 19564 ? Sl
>> 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\n25593\n25595\n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n25694\n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \nroot 26239 0.0 0.1 5813460 19452 ?
>> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\n26239\n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \nroot 26319 0.0 0.1 5811252 15484 ?
>> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\n26319\n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>> "We will kill these processes: \n"
>>
>>
>> I have Supervisord set to run 3 instances of the sarr app, so you can see
>> at first it it is killing these PIDs:
>>
>> 25593
>> 25595
>> 25694
>>
>> Supervisord restarts these almost instantly, so you can see these
>> processes are launched and instantly killed, all on the same line of
>> output:
>>
>> "We will kill these processes: \nroot 26239 0.0 0.1 5813460 19452 ?
>> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\n26239\n"
>>
>> "We will kill these processes: \nroot 26319 0.0 0.1 5811252 15484 ?
>> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
>> com.candle.sarr.Main\n26319\n"
>>
>> This goes on for as long as I allow it (it takes Supervisord a long time
>> to quit, because when I am developing new software, I set startretries=500,
>> in Supervisord, exactly so I can experiment like this).
>>
>> I looked here to try to figure out what was going on:
>>
>>
>> https://github.com/zcaudate/hara/blob/55b4eda688a4e616f03bf3740419a69b5c5dd658/src/hara/io/watch.clj
>>
>> As near as I can tell, the main action happens here:
>>
>> (defn run-watcher [watcher]
>> (let [^java.nio.file.WatchKey wkey
>> (.take ^java.nio.file.WatchService (:service watcher))]
>> (doseq [^java.nio.file.WatchEvent event (.pollEvents wkey)
>> :when (not= (.kind event)
>> StandardWatchEventKinds/OVERFLOW)]
>> (let [kind (.kind event)
>> ^java.nio.file.Path path (.watchable wkey)
>> ^java.nio.file.Path context (.context event)
>> ^java.nio.file.Path res-path (.resolve path context)
>> ^java.io.File file (.toFile res-path)]
>> (if (and (= kind StandardWatchEventKinds/ENTRY_CREATE)
>> (.isDirectory file)
>> (-> watcher :options :recursive))
>> (register-sub-directory watcher (.getPath file)))
>> (if (.isFile file)
>> (process-event watcher kind file))))
>> (.reset wkey)
>> (recur watcher)))
>>
>>
>> Again, maybe I am being stupid, but it looks to me like the callback is
>> called once per event triggered on that directory. So why would the
>> callback seem to be called an infinite number of times? Does starting or
>> stopping the app trigger a change in the directory (thus triggering the
>> callback again)?
>>
>>
>>
>>
>>
>>
>>
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