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When killing a virtual machine, sql_logs/sql/log is empty #3928

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

When killing a virtual machine, sql_logs/sql/log is empty #3928

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

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

Date: 2016-02-19 09:35:06 +0100
From: anthonin.bonnefoy
To: GDK devs <>
Version: 11.21.5 (Jul2015)

Last updated: 2016-03-25 09:59:09 +0100

Comment 21805

Date: 2016-02-19 09:35:06 +0100
From: anthonin.bonnefoy

User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0 Iceweasel/45.0
Build Identifier:

As summary says, when a virtual machine is killed, sql_logs/sql/log is empty on reboot.

The file is closed using fclose, that does not ensure the flush of kernel buffers.
In gdk_logger.c, adding the following lines seems to do the trick.

                     logger_fatal("logger_new: writing log file %s failed",
                                  filename, 0, 0);
             }
  •           if (fsync(fileno(fp)) < 0) {
    
  •                   unlink(filename);
    
  •                   logger_fatal("logger_new: Fsync %s failed",
    
  •                                filename, 0, 0);
    
  •           }
              if (fclose(fp) < 0) {
                      unlink(filename);
                      logger_fatal("logger_new: closing log file %s failed",
    

Reproducible: Always

Steps to Reproduce:

  1. Start a virtual machine (i used qemu)
  2. Create and start a dabase on it
  3. Kill the virtual machine (just a CTRL-C is enough)

Actual Results:

On reboot, sql_logs/sql/log is empty

Comment 21806

Date: 2016-02-19 10:18:46 +0100
From: MonetDB Mercurial Repository <>

Changeset 0074383d6391 made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=0074383d6391

Changeset description:

Make sure important data is on disk.
This fixes bug #3928.

Comment 21807

Date: 2016-02-19 10:20:41 +0100
From: @sjoerdmullender

I fixed this by indeed calling fsync (or fdatasync or _commit, depending on availability of system calls), but before doing that, we need to call fflush, or else the fsync still won't do anything.

Comment 21955

Date: 2016-03-25 09:59:09 +0100
From: @sjoerdmullender

Jul2015-SP3 has been released.

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