Bug 80858 - journalctl misbehaves when wall clock is changed
Summary: journalctl misbehaves when wall clock is changed
Status: NEW
Alias: None
Product: systemd
Classification: Unclassified
Component: general (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: systemd-bugs
QA Contact: systemd-bugs
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-07-03 14:49 UTC by Marius Vollmer
Modified: 2015-06-01 18:32 UTC (History)
1 user (show)

See Also:
i915 platform:
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Attachments
test program. (1.66 KB, text/plain)
2014-07-03 14:49 UTC, Marius Vollmer
Details

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Description Marius Vollmer 2014-07-03 14:49:15 UTC
Created attachment 102202 [details]
test program.

With a specific set of journal files, we are seeing some odd behavior.  The journal files cover multiple boots and have walltime discontinuities in them.

I'll send the journal files on request.

$ journalctl -D XXX/var/log/journal/ --cursor 's=de164a5e12e64f03b334128e4542ec9a;i=edb36;b=88b9ffdd4d2c40c1836f4a4d11c7d2bc;m=145f5aa0ae;t=4fc1b3c1b82f7;x=cf69db9bc053ff06' -u NetworkManager --show-cursor | tail -1
-- cursor: s=a6243fe62e0d45939c17eb9cb76f8812;i=11c34e;b=3e5244c588534eb4b4f3645d56b011c1;m=260accecf9;t=4fd38316fe7ed;x=38925d7bd704ad1d
$ journalctl -D XXX/var/log/journal/ --cursor 's=a6243fe62e0d45939c17eb9cb76f8812;i=11c34e;b=3e5244c588534eb4b4f3645d56b011c1;m=260accecf9;t=4fd38316fe7ed;x=38925d7bd704ad1d' -u NetworkManager --show-cursor | tail -1
-- cursor: s=de164a5e12e64f03b334128e4542ec9a;i=edb36;b=88b9ffdd4d2c40c1836f4a4d11c7d2bc;m=145f5aa0ae;t=4fc1b3c1b82f7;x=cf69db9bc053ff06

Thus, there are two cursors, and starting from one ends up at the other.

Also, doing sd_journal_seek_tail(), sd_journal_skip_previous(10) and then looping over sd_journal_next until it returns 0 will happily loop over thousands of entries, instead of the expected 10.

I attach a small program that combines these effects to get into an endless loop, although it works correctly for most journal files.
Comment 1 Philip Donlon 2014-07-03 15:12:36 UTC
Here are the journal files that produce the loop:

https://drive.google.com/file/d/0B_MyU2g8XYMrR2RQSndTTVlMNzA/edit?usp=sharing
Comment 2 Marius Vollmer 2014-07-04 06:40:11 UTC
Forgot to mention: This only fails with a match.  Without the '-u' option, this happens:

$ journalctl -D XXX/var/log/journal/ --cursor 's=a6243fe62e0d45939c17eb9cb76f8812;i=11c34e;b=3e5244c588534eb4b4f3645d56b011c1;m=260accecf9;t=4fd38316fe7ed;x=38925d7bd704ad1d' --show-cursor | tail -1
-- cursor: s=a6243fe62e0d45939c17eb9cb76f8812;i=11c363;b=3e5244c588534eb4b4f3645d56b011c1;m=261ef68e3f;t=4fd3845998933;x=84b1b3c1b922ad2e
$ journalctl -D XXX/var/log/journal/ --cursor 's=a6243fe62e0d45939c17eb9cb76f8812;i=11c363;b=3e5244c588534eb4b4f3645d56b011c1;m=261ef68e3f;t=4fd3845998933;x=84b1b3c1b922ad2e' --show-cursor | tail -1
-- cursor: s=a6243fe62e0d45939c17eb9cb76f8812;i=11c363;b=3e5244c588534eb4b4f3645d56b011c1;m=261ef68e3f;t=4fd3845998933;x=84b1b3c1b922ad2e

Thus, no looping between cursors.
Comment 3 George McCollister 2014-09-23 19:56:04 UTC
Has anyone looked into this problem?


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