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Thread log file analysis
Thu, Mar 9 2006 1:02 AMPermanent Link

"Al VAs"
Hi,

Can anyone give me ideas on why the following might occur?  We have a subset
of our clients on the 3.30 server engine and 1 particular client is
experiencing the our application locking all users.  A look at the database
server log shows issues as below.  It appears the an access violation occurs
in the engine and all PC connections get closed.  Is this most likely an
environment issue?  Have noticed when logged into their server via terminal
services that sometimes the server stops responding for periods of time up
to 20-30 seconds.

9/03/2006 3:23:38 PM Engine error - Access violation at address 0049F7F0 in
module 'dbsrvr.exe'. Read of address 00000008 [Address: 192.168.16.16
Version: 3.30 Request: REQUEST_EXECUTESTMT Thread: 2056 Session: 0]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.16 Version: 3.30
Thread: 2056 Session: 0]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.12 Version: 3.30
Thread: 2316 Session: 316083460]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.12 Version: 3.30
Thread: 3896 Session: 316047592]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.10 Version: 3.30
Thread: 5604 Session: 315505856]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.10 Version: 3.30
Thread: 1092 Session: 162085708]
9/03/2006 3:23:38 PM Connection closed [Address: 192.168.16.20 Version: 3.30
Thread: 5812 Session: 70926312]
9/03/2006 3:23:39 PM Connection closed [Address: 192.168.16.20 Version: 3.30
Thread: 1536 Session: 315469988]

Thanks

Alex

Thu, Mar 9 2006 3:48 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Alex,

<< Can anyone give me ideas on why the following might occur?  We have a
subset of our clients on the 3.30 server engine and 1 particular client is
experiencing the our application locking all users.  A look at the database
server log shows issues as below.  It appears the an access violation occurs
in the engine and all PC connections get closed.  Is this most likely an
environment issue?  Have noticed when logged into their server via terminal
services that sometimes the server stops responding for periods of time up
to 20-30 seconds. >>

Do you know what SQL statement is being executed or what area of the client
application is executing when the error occurs ?

--
Tim Young
Elevate Software
www.elevatesoft.com

Thu, Mar 9 2006 4:37 PMPermanent Link

"Al Vas"
Hi Tim,

No unfortunately I dont.  So you think it could be an SQL statement causing
the access violation?  I'm not too sure that this is the cause as we have 5
or 6 clients on the exact same version with no such issues.  It has
happening to this client 2-3 or more times a day.

Am I reading this right in saying that an access violation is occurring in
the database engine server, which then shuts down and forces out all users?

Thanks

Alex
"Tim Young [Elevate Software]" <timyoung@elevatesoft.com> wrote in message
news:3C7AED76-5F39-46DA-9AF1-E8A7B0785BA9@news.elevatesoft.com...
> Alex,
>
> << Can anyone give me ideas on why the following might occur?  We have a
> subset of our clients on the 3.30 server engine and 1 particular client is
> experiencing the our application locking all users.  A look at the
> database server log shows issues as below.  It appears the an access
> violation occurs in the engine and all PC connections get closed.  Is this
> most likely an environment issue?  Have noticed when logged into their
> server via terminal services that sometimes the server stops responding
> for periods of time up to 20-30 seconds. >>
>
> Do you know what SQL statement is being executed or what area of the
> client application is executing when the error occurs ?
>
> --
> Tim Young
> Elevate Software
> www.elevatesoft.com
>
>

Fri, Mar 10 2006 4:10 AMPermanent Link

Eryk Bottomley
Al,


> No unfortunately I dont.  So you think it could be an SQL statement causing
> the access violation?

9/03/2006 3:23:38 PM Engine error - Access violation at address 0049F7F0 in
module 'dbsrvr.exe'. Read of address 00000008 [Address: 192.168.16.16
Version: 3.30 Request: REQUEST_EXECUTESTMT Thread: 2056 Session: 0]

....the command code there ("REQUEST_EXECUTESTMT") means "Request
Execution (of SQL) Statement".

Eryk
Fri, Mar 10 2006 5:19 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Alex,

<< No unfortunately I dont.  So you think it could be an SQL statement
causing  the access violation? >>

It's definitely an SQL statement due to what the log says.

<< Am I reading this right in saying that an access violation is occurring
in the database engine server, which then shuts down and forces out all
users? >>

It's occurring in the database server, but I'm not sure if it's forcing out
all of the users.  I've never seen the DBISAM database server do that for
any reason other than it is shutting down.

--
Tim Young
Elevate Software
www.elevatesoft.com

Sat, Mar 11 2006 11:22 PMPermanent Link

"Al Vas"



Attachments: perflog.jpg
Mon, Mar 13 2006 12:02 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Alex,

<< We seem to getting a bit further with this.  The IT network administrator
ran a performance monitor for a couple of days.  Just for your info, I hope
you dont mind, I have attached a certain section of it, which shows a
potential issue.  According to the network person the following
observations, actions and questions were made:

there is a moment in the last hour of the log where it looks like the memory
hits %100 of the total available.  Its interesting because the task manager
does not indicate anything close.  Infact it only indicates about 500Mb is
actually being used. >>

What does the task manager show for virtual memory used  for the dbsrvr
process (VM Size column in the task manager, not the Mem Usage column) ?
Also, is this 3.30 or 3.21 still ?

<< Question:  What is the required memory per user connected? ?? >>

It depends upon the number of open tables per session.  Basically, if using
the default memory buffering settings, you can use this formula:

256k * Number of Open Tables Per Session * Number of Sessions Present on the
Database Server

<< Question:  Is increasing the virtual memory enough to eleviate this if
indeed, a lack of memory is causing the problem. >>

My guess is that there's either a) a memory leak in DBISAM that you are
encountering or b) something else is consuming the memory.

--
Tim Young
Elevate Software
www.elevatesoft.com

Mon, Mar 13 2006 11:47 PMPermanent Link

"Al VAs"
Hi Tim,

What is the VM Size column?  There doesnt appear to be one in Task Manager.
We are using V3.30 of the DB engine.  We have not pathed with the new pas
file yet as our developer went on holidays before we received it.  We will
be patching in the next couple of days, but presume this wont have any
affect on this particular issue.

Memory leak in DBISAM, would you think that might be an engine issue or a
programmatic issue?  There is always the potential that it is something else
consuming the memory.

Alex

"Tim Young [Elevate Software]" <timyoung@elevatesoft.com> wrote in message
news:AF3B0343-E1DC-480F-96E7-3B277B625D3F@news.elevatesoft.com...
> Alex,
>
> << We seem to getting a bit further with this.  The IT network
> administrator ran a performance monitor for a couple of days.  Just for
> your info, I hope you dont mind, I have attached a certain section of it,
> which shows a potential issue.  According to the network person the
> following observations, actions and questions were made:
>
> there is a moment in the last hour of the log where it looks like the
> memory hits %100 of the total available.  Its interesting because the task
> manager does not indicate anything close.  Infact it only indicates about
> 500Mb is actually being used. >>
>
> What does the task manager show for virtual memory used  for the dbsrvr
> process (VM Size column in the task manager, not the Mem Usage column) ?
> Also, is this 3.30 or 3.21 still ?
>
> << Question:  What is the required memory per user connected? ?? >>
>
> It depends upon the number of open tables per session.  Basically, if
> using the default memory buffering settings, you can use this formula:
>
> 256k * Number of Open Tables Per Session * Number of Sessions Present on
> the Database Server
>
> << Question:  Is increasing the virtual memory enough to eleviate this if
> indeed, a lack of memory is causing the problem. >>
>
> My guess is that there's either a) a memory leak in DBISAM that you are
> encountering or b) something else is consuming the memory.
>
> --
> Tim Young
> Elevate Software
> www.elevatesoft.com
>
>

Tue, Mar 14 2006 2:56 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Al


If you're looking for memory leaks try compiling with FastMM4, running it in the IDE and closing down - you'll get a list of the problem areas.

The other one I've used is memcheck also very good.


Roy Lambert
Tue, Mar 14 2006 12:56 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Alex,

<< What is the VM Size column?  There doesnt appear to be one in Task
Manager. >>

You might have to add it using View|Select Columns.

<< We are using V3.30 of the DB engine.  We have not pathed with the new pas
file yet as our developer went on holidays before we received it.  We will
be patching in the next couple of days, but presume this wont have any
affect on this particular issue. >>

There was this leak in 3.21:

http://www.elevatesoft.com/scripts/incident.dll?action=viewrep&release=3.21&type=f&incident=1325

<< Memory leak in DBISAM, would you think that might be an engine issue or a
programmatic issue?  There is always the potential that it is something else
consuming the memory. >>

The only thing besides an actual bug in DBISAM that could cause what appears
to be a leak would be a situation where one is a) constantly modifying the
buffering parameters in an upward fashion or b) creating in-memory tables
constantly without dropping them when they are no longer needed.

--
Tim Young
Elevate Software
www.elevatesoft.com

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