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Incorrect crash time reported by monetdb tool after crash of mserver5 #6796

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monetdb-team opened this issue Nov 30, 2020 · 0 comments
Closed

Incorrect crash time reported by monetdb tool after crash of mserver5 #6796

monetdb-team opened this issue Nov 30, 2020 · 0 comments

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@monetdb-team monetdb-team commented Nov 30, 2020

Date: 2019-12-05 21:30:20 +0100
From: Olaf Flaschel <<olaf.flaschel>>
To: Merovingian devs <>
Version: 11.35.3 (Nov2019)

Last updated: 2019-12-20 15:36:32 +0100

Comment 27454

Date: 2019-12-05 21:30:20 +0100
From: Olaf Flaschel <<olaf.flaschel>>

User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0
Build Identifier:

While investigating a crash of mserver5 I remarked that the monetdb tool reports an incorrect crash time. It seems to report the time when the database was started and not the time when the database (mserver5 instance) crashed.

Reproducible: Always

Steps to Reproduce:

  1. Create a new database: sudo monetdb create test
  2. Release the database: sudo monetdb release test
  3. Start the database: sudo monetdb start test
  4. Wait 5 minutes
  5. Find out pid of mserver5 instance: ps -ef | grep mserver5
  6. Kill mserver5 instance and print current time: sudo kill -9 ;date
  7. Check status of database: sudo monetdb monetdb status
  8. Compare time shown in 6. and time reported by monetdb

Actual Results:

The monetdb tool reports time when database was started.

Expected Results:

The monetdb tool should report the time when the database crashed.

monetdb --version
MonetDB Database Server Toolkit v11.35.3 (Nov2019)

Comment 27456

Date: 2019-12-06 14:31:31 +0100
From: @sjoerdmullender

The report is indeed confusing.
Currently we don't know at what time the server crashed, we only know when it was started and that it crashed.
Of course, mserver5 can't tell monetdbd that it is about to crash (especially not if you kill it with kill -9), so we need to figure it out in some other way. What we should probably do is catch the SIGCHILD signal, but that'll take some effort to implement (catching isn't hard, avoiding the resulting race conditions is).

Comment 27469

Date: 2019-12-10 09:36:36 +0100
From: Olaf Flaschel <<olaf.flaschel>>

(In reply to Sjoerd Mullender from comment 1)

The report is indeed confusing.
Currently we don't know at what time the server crashed, we only know when
it was started and that it crashed.
Of course, mserver5 can't tell monetdbd that it is about to crash
(especially not if you kill it with kill -9), so we need to figure it out in
some other way. What we should probably do is catch the SIGCHILD signal,
but that'll take some effort to implement (catching isn't hard, avoiding the
resulting race conditions is).

Maybe just changing the message would be enough:

"crashed (started on 2019-12-05 21:06:43)"

or

"crashed"

instead of

"crashed on 2019-12-05 21:06:43"

Comment 27472

Date: 2019-12-10 16:45:57 +0100
From: MonetDB Mercurial Repository <>

Changeset 2ea938bafd98 made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=2ea938bafd98

Changeset description:

Fixed wording of status information after crash.
This fixes bug #6796.

Comment 27473

Date: 2019-12-10 16:49:32 +0100
From: @sjoerdmullender

I've implemented your suggestion.

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