Bug 23813 - Make "too many pending warnings" more helpful
Summary: Make "too many pending warnings" more helpful
Status: UNCONFIRMED
Alias: None
Product: systemtap
Classification: Unclassified
Component: runtime (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Unassigned
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-10-24 04:47 UTC by agentzh
Modified: 2018-10-24 18:52 UTC (History)
1 user (show)

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Description agentzh 2018-10-24 04:47:20 UTC
Some times we only get something like below from stap:

```
WARNING: too many pending (warning) messages
ERROR: too many pending (error) messages
WARNING: /opt/stap-plus/bin/staprun exited with status: 1
Pass 5: run failed.  [man error::pass5]
```

It's not helpful at all since we have no idea what messages are actually flooding the control message buffers.

We should make stap output the first few and also the last few messages in the current control buffer when it thinks that there are "too many". Otherwise there is no way to debug things here.
Comment 1 Frank Ch. Eigler 2018-10-24 18:14:54 UTC
These messages are printed when the rate of the messages is so high that there wasn't room to store any more of them.  Maybe the suggestion is to drop -earlier- ones rather than new ones?  Not sure how easy that would be.
Comment 2 agentzh 2018-10-24 18:47:33 UTC
As long as we output some warning messages from the buffer at least. Right now I don't see any warnings at all generated, which makes debugging near impossible if without tracing stap itself...
Comment 3 Frank Ch. Eigler 2018-10-24 18:50:28 UTC
I wonder if you have a reproducer handy.  A few attempts here always resulted in some real payload WARNINGs' before the "too many" ones.
Comment 4 agentzh 2018-10-24 18:52:42 UTC
Yeah, it seems only reproducible in our big examples. I'll try digging a bit myself...