 23 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
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The following script makes midas very unhappy and eventually causes odb corruption. I suspect the reason is some kind of race condition collision between
client
creation and destruction code and the watchdog activity (each client periodically runs cm_watchdog() to check if other clients are still alive, O(NxN) |
 24 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
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> Thu Dec 23 12:10:30 2010 [ODBEdit9,ERROR] [odb.c:3247:db_get_value,ERROR] "Name" is of type NULL, not STRING
This is caused by a race condition between client removal in cm_delete_client_info() and cm_exist().
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24 Dec 2010, Konstantin Olchanski, Bug Report, odb corruption, odb race condition?
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> > Thu Dec 23 12:10:30 2010 [ODBEdit9,ERROR] [odb.c:3247:db_get_value,ERROR] "Name" is of type NULL, not STRING
> This is caused by a race condition between client removal in cm_delete_client_info() and cm_exist().
> ... this race condition seems to be benign.
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26 Dec 2010, Konstantin Olchanski, Bug Report, race condition and deadlock between ODB lock and SYSMSG lock in cm_msg()
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>
> The only remaining problem when running my script is some kind of deadlock between the ODB and SYSMSG semaphores...
>
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29 Dec 2010, Konstantin Olchanski, Bug Report, use of nested locks in MIDAS
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A "nested" or "recursive" lock is a special type of lock that permits a lock holder to lock the same resources again and again, without deadlocking on itself.
They are
very useful, but tricky to implement because most system lock primitives (SYSV semaphores, POSIX mutexes, etc) do not permit nested locks, so all the logic |
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29 Dec 2010, Konstantin Olchanski, Bug Report, fixed. odb corruption, odb race condition?
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>
> The only remaining problem when running my script is some kind of deadlock between the ODB and SYSMSG semaphores...
>
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11 Feb 2011, Konstantin Olchanski, Bug Report, fixed. odb corruption, odb race condition?
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> >
> > The only remaining problem when running my script is some kind of deadlock between the ODB and SYSMSG semaphores...
> >
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15 Feb 2011, Konstantin Olchanski, Bug Report, fixed. odb corruption, odb race condition?
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> Solution shall follow quickly, I have been hunting this deadlock for the last couple of weeks...
Over the last couple of days I made a series of commits to odb.c and midas.c to implement a buffer-based cm_msg()
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15 Feb 2011, Konstantin Olchanski, Bug Fix, mlogger stop run on disk full!
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The mlogger has a function for detecting when the output disk becomes full - when this condition is
detected, the run should be stopped. But this did not work if disk is already full and the user tries to start
a run - the "disk full?" check happened too early and the attempt to stop the run was not succeeding
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16 Feb 2011, Konstantin Olchanski, Info, Notes on MIDAS history
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Some notes on the MIDAS history.
MIDAS documentation at
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16 Feb 2011, Konstantin Olchanski, Bug Report, Problems with midas history SVN 4936
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> I have the following problems after updating to midas SVN 4936: the history
> system (web-page via mhttpd) seems to stop working. I checked the history files
> themself and they are indeed written, except that the events ID's are not the
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16 Feb 2011, Konstantin Olchanski, Bug Report, Problems with midas history SVN 4936
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It looks like email notices did not go the first time. Please read my replies below. K.O.
> > I have the following problems after updating to midas SVN 4936: the history
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16 Feb 2011, Konstantin Olchanski, Bug Report, Problems with midas history SVN 4936
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>
> Do you mind giving little more detail? We might have the same issue, where we got
> complaints that midas history stops working after a certain time.
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16 Feb 2011, Konstantin Olchanski, Info, Notes on MIDAS history
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>
> 1) PerVariableHistory.
>
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16 Feb 2011, Konstantin Olchanski, Bug Report, fixed. odb corruption, odb race condition?
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> My torture test runs okey in my mac now, one remaining problem is spurious client removal caused
> by semaphore starvation...
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28 Feb 2011, Konstantin Olchanski, Info, javascript example experiment 
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I just committed a MIDAS example for using most mhttpd html and javascript functions: ODBGet(),
ODBSet(), ODBRpc() & co.
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15 Apr 2011, Konstantin Olchanski, Forum, How large does "bank32" support?
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> Reading an FADC buffer often needs large buffer size, especially while several
> FADCs work together. I want to know how large a bank32 can support.
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17 Jun 2011, Konstantin Olchanski, Forum, ladd00.triumf.ca https ssl certificate update
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The HTTPS SSL certificate on ladd00.triumf.ca has been updated. Same as the old
certificate, the new one is self-signed and your web browser may complain about
that and ask you to "save a security exception".
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27 Jun 2011, Konstantin Olchanski, Suggestion, Build MIDAS debian packages using autoconf/automake.
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> I deployed several Debian Linux boxes as the DAQ systems in our lab. But I
feel it's boring to build and install midas and its related softwares (such as
root) on each box.
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27 Jun 2011, Konstantin Olchanski, Info, updated mhttpd history "export" function
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The mhttpd history "export" function has been converted to the new midas history
interface and should now work for SQL-based history systems. In the process,
improvements by Eoin Butler (CERN AD-5/ALPHA) were merged - adding a UNIX
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