run gets stuck when output is redirected to a pipe

Bug #1801352 reported by Dr. Jens Harbott
This bug affects 2 people
Affects Status Importance Assigned to Milestone

Bug Description

This is a new issue, I haven't seen this issue until a week ago. I also only saw it on Bionic so far, so possibly it is an issue with some other Ubuntu component and not with devstack.

What happens is that I'm running 2>&1 | tee -a stack1.log

as my usual invocation to deploy devstack and saving the complete log output including stderr. This used to work fine before, but now I am seeing the tee process getting stuck, seemingly waiting for further input, once the job has ended. This happens both after a failure as well as after a successful completion. The issue also occurs if I omit the "2>&1" part.

Revision history for this message
Ian Wienand (iwienand) wrote :

hrm, when I duplicated this basic stuff into diskimage-builder, I had a couple of problems with the prompt getting all mixed up with the final output, which made me put a sleep in [1]

I started looking a co-processes but didn't get very far.


Revision history for this message
Dr. Jens Harbott (j-harbott) wrote :

There are no processes left running when I get into the error condition except for the "tee" process.

It seems that if I add a "sleep 1" at the end of, the issue goes away, so maybe we should just use that workaround in devstack, too.

Changed in devstack:
status: New → Triaged
importance: Undecided → Low
Changed in devstack:
assignee: nobody → HanGuangyu (hanguangyu)
Revision history for this message
Han Guangyu (han-guangyu) wrote (last edit ):

I can't reproduct it in uos-server-1020a which is a downstream of CentOS8.

Changed in devstack:
assignee: HanGuangyu (hanguangyu) → nobody
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