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Jenkins console output not in realtime

Pretty new to Jenkins and I have simple yet annoying problem. When I run job (Build) on Jenkins I am triggering ruby command to execute my test script.

Problem is Jenkins is not displaying output in real time from console. Here is trigger log.

Building in workspace /var/lib/jenkins/workspace/foo_bar No emails were triggered. [foo_bar] $ /bin/sh -xe /tmp/hudson4042436272524123595.sh + ruby /var/lib/jenkins/test-script.rb 

Basically it hangs on this output until build is complete than it just shows full output. Funny thing is this is not consistent behavior, sometimes it works as it should. But most of the time there is no real time console output.

Jenkins version: 1.461

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Haris Krajina Avatar asked Jul 24 '12 13:07

Haris Krajina


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Where does Jenkins store console output?

Jenkins stores the console log on master. If you want programmatic access to the log, and you are running on master, you can access the log that Jenkins already has, without copying it to the artifacts or having to GET the http job URL.


1 Answers

To clarify some of the answers.

  • ruby or python or any sensible scripting language will buffer the output; this is in order to minimize the IO; writing to disk is slow, writing to a console is slow...
  • usually the data gets flush()'ed automatically after you have enough data in the buffer with special handling for newlines. e.g. writing a string without newline then sleep() would not write anything until after the sleep() is complete (I'm only using sleep as an example, feel free to substitute with any other expensive system call).

e.g. this would wait 8 seconds, print one line, wait 5 more seconds, print a second line.

from time import sleep  def test():     print "ok",     time.sleep(3)     print "now",     time.sleep(5)     print "done"     time.sleep(5)     print "again"  test() 
  • for ruby, STDOUT.sync = true, turns the autoflush on; all writes to STDOUT are followed by flush(). This would solve your problem but result in more IO.

    STDOUT.sync = true 
  • for python, you can use python -u or the environment variable PYTHONUNBUFFERED to make stdin/stdout/stout not buffered, but there are other solutions that do not change stdin or stderr

    export PYTHONUNBUFFERED=1 
  • for perl, you have autoflush

    autoflush STDOUT 1; 
like image 94
dnozay Avatar answered Sep 21 '22 08:09

dnozay