Jenkins console output not in realtime

Question

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

user_2693875 · Answer

For some commands, including tee a the best choice for unbuffering is a program called unbuffer from expect package.

Usage example:

instead of

somecommand | tee /some/path

do

somecommand | unbuffer -p tee /some/path

Sources and more info:

user_7906993 · Answer

Python buffered its output traces and print it at the end of script to minimize writing on console as writing to console is slow.

You can use following command after your traces. It will flush all traces to console, which are queued before that command.

sys.stdout.flush()

Jenkins console output not in realtime

9 Answers