error - too many client tasks

[Simonbullen]

hi, I am getting this error,

error executing database query.
[Macromedia][SequeLink JDBC Driver][ODBC Socket][Microsoft][ODBC Microsoft
Access Driver] Too many client tasks.

does anybody know what is causing it and how to fix it please as when it
happens it throws out all of my coldfusion reliant sites!!

thank you!

[Dai Wei]

> error executing database query.

> [Macromedia][SequeLink JDBC Driver][ODBC Socket][Microsoft][ODBC Microsoft
> Access Driver] Too many client tasks.
> does anybody know what is causing it and how to fix it please as when it
> happens it throws out all of my coldfusion reliant sites!!

MS Access supports at most 255 clients, so that you should check
whether you have called Connetion.close() and ResultSet.close() in time.

[ecolucci]

I receive the same error as Simonbullen although I receive a second--but
apparently related--error more frequently that reads "Error Executing Database
Query. coldfusion.sql.DatabaseConnectionException: Timed out trying to
establish connection." We use CFMX 6.1 server with Windows 2003 on a two-way
server. These errors did not appear on our old server that had CF 5 with
Windows NT 4. These errors occur sporadically and only with our Microsoft
Access data-base connections (not with our Oracle connections), and I have not
been able to reproduce them (at will) to date.

A Google search yielded only one clue to the problem on the following Web page
[url]http://www.petefreitag.com/item/194.cfm[/url]. I followed the suggesstion to "set
your Datasource setting Limit Connections to no more than 8 connections," and
we currently have the Maximum number of simultaneous requests setting in
ColdFusion Administrator set to 5.

This adjustment had no noticeable effect, and the errors continue to occur
resulting in any CF page dependent on a data-base query to hang indefinitely.
My temporary "solution" is to cycle through the CF services via a script. It
seems that breaking the connection between the CF server and the MSDE "resets"
the MSDE, and everything works again, but this "solution" is not acceptable on
a production server. I too can use help resolving this situation.

[phil_dude]

Has anyone found a solution to this problem. We launched a new server months ago and this problem remains.

[Simonbullen]

are you using access?
the problem for me casued because Access can only handle a cetrain amount of
processes at once and the error came up when too many were performed, my
solution has been to use SQL for my larger database jobs and just save access
for database use were it won't get too many people using the daatbase at the
same time, hope this helps

[SafariTECH]

Access is not recommended for anything other than extremely low traffic sites -
many ISPs won't even allow them any longer.

I think Simonbullen has basically hit the nail on the head - you are getting
too many requests for the drivers to handle.

You might be able to alleviate some of the traffic hits (if you have queries
that are always identical) by using the cachedWithin attribute for your queries.

[jorgepino]

there is no solution for this problem
MSaccess is not made to handle to many request, it was build for destop access
if you have a choice you should upgrade to MSslq or Mysql

[bfharris]

It is rediculous to say Access can't handle it.
We use Access as our database on a server with a retail site doing over 1
million dollars in sales a year.
However, we just upgraded that server as well as our backoffice server to
Win2K3 with both using CFMX6.1.
With CFMX6.1 and Win2K we never had a problem. Now the backoffice server, not
both, is seeing this issue. There are no other erros and nothing is different
other than the upgrade to Win2K3. Like I said though, the servers are
identical, but one is having the issue and the other isn't. Makes no sense.

[ecolucci]

In our situation the problem in this thread is very closely related to the
problem in the thread "Error Executing Database Query. Timed out trying to
establish connection" so I will repeat my most current post in that other
thread here (with minor modifications). Before I do that however, I want to
correct a misstatement in my post above: Whenever I referenced MSDE, I should
have referenced Jet (data-base engine).



Our experience of the problem is that its onset is apparently random.
However, I can eliminate the problem temporarily while it occurs by recycling
all three CFMX 6.1 services (via an executable command file). If I am not
aware of the problem for whatever reason, the problem self-corrects after a
certain, unknown period of time that is greater than 1 minute but less than 20
minutes. In my conversations with Macromedia support, a technician recommended
to me that I use the Microsoft Access with Unicode DB driver instead of the
Microsoft Access DB driver, but I discovered that other code that previously
worked now did not (beginning with INSERT statements in my queries).

Conversations with a Microsoft technician suggested the problem might be
permissions related in that I did not grant appropriate access to the account
under which the w3wp.exe process executes in IIS 6. After investigating this
matter and granting appropriate permissions, the problem persists.

With regard to Bfharris' comments above, Access does have known limitations
with regard to concurrent connections (and other limitations relative to an
enterprise DBMS) so it is true that in certain situations Access is not up to
the task. My numerous conversations with Microsoft technical personnel more
than corroborate this statement. (You can check MS Technet for confirmation.)

However, the problem we are experiencing does not appear to be the result of
any Access limitations (since our Access data bases worked just fine for years
until our migration to Windows 2003 and CFMX 6.1 early this year). The problem
appears to have something to do with the Access DB drivers provided by
Macromedia and their inability to reliably "communicate" with MS Access DBs via
an JDBC-ODBC bridge. The "solution" (according to both Macromedia and
Microsoft technicians with whom I spoke between August and September of this
year) is to use an enterprise-level DBMS whereby the Macromedia (or native) DB
drivers can communicate more reliably with the DB.

Since my last post, we decided to migrate to MS SQL Server, which for our
environment looks as though will be the best move. MS SQL Server will permit
our MS Access power users to continue to manipulate data-base objects in MS SQL
Server pretty much as they did in the past. Migrating to an enterprise-level
DBMS still appears to be the only "solution" to this problem.

[brolland]

Does anyone have any other solutions? Migrating to SQL Server is not an option
for us, as the project I'm working on is important but tiny!

I have a CF page with 15 recordsets. These are small, basic, uncomplicated
queries that hit an Access database on my network. I've been working on this
CF page with these same queries for weeks with no problems. All I do on this
page is chart the 15 queries and dump the data. Sometimes it works, sometimes
I get the "too many client tasks" error. We have to restart the server each
time to get it to work again, then it works a couple of times and stops
working. Argh.

[ksmith]

Hi,
The forum members telling you that access is the issue, are correct. Access
is a desktop database that is meant to have a single connection made to it.
It is not meant to be connected to a high speed application server. You
indicate you have a simple page doing 15 queries. That is going to be too much.

Microsoft originally distributed windows 2003 without the msjet and odbc
drivers to connect to access and foxpro. They indicated that these desktop
databases were inappropriate for use on a high speed server operating system.
The mdac 2.8 distributable still lacks those drivers for just that reason.
Similarly, it is bad design to create CFMX applications to run against access,
unless they do very little database activity. This would not include making 15
queries on a single page.

That said, the things you can do are:
In the advanced settings of your datasource in the cfadmin, make sure the
maintain database connections is turned off. Also check the limit connections
checkbox and limit the connections to 1.
You can also upgrade to the latest version of the macromedia JDBC drivers and
the latest version of the ODBC sequelink.
[url]http://www.macromedia.com/go/e917887[/url]

Should the steps above fail, you could also try using the a new datasource
created using the "Microsoft Access with Unicode" driver type. This uses a
jdbc to oledb bridge to the MSAccess ole driver. Your current access
connection is through a JDBC driver to an JDBC/ODBC bridge to the access odbc
driver.

If those fail, you may be able to get the 15 query page to work by putting
sleeps in between each cfquery. That can be done with the following code:



<!--- Creates a java object of type Thread --->
<cfset thrObj = CreateObject("java","java.lang.Thread")>

<!--- Calls the Thread objects sleep method to pause 2 seconds --->
<cfset thrObj.sleep(2000)>

[paross1]

If SQL Server isn't an option, you could try MySQL (as Jorge Pino previously
suggested). It is becoming a pretty good database, and it doesn't suffer from
the kinds of problems that you are having with Access (and the price is right).

Phil

[brolland]

Thanks for all the info. The funny/interesting thing is that these same 15
queries on the page worked for weeks and are just now starting to be an issue.
Why? The only thing that changed on the page is that I started using variables
in the queries instead of hard-coded values. For example, instead of
dept='Ling' I now say dept=#URL.dept#. I'm going to go back to my earlier
versions with the hard-coded values and see if those work.

The data I'm charting isn't just for my application, it's university-wide data
that they want to stay in Access, I think. These charts will be accessed maybe
a couple of times/month by one or two people, not exactly a high-traffic site.

Thanks for the ideas, Ken. I'll give those a try and see what happens.

Betsy

[brolland]

So, it's now working again. We changed one of the administration settings,
something about threads I think, rebooted CF and haven't had any problems
since. (We had also changed a couple of other settings earlier but not
rebooted CF, so it could've been one of those settings!)

I can run my 15 queries full of variables in one page against my Access
database and create my 6 different charts. We're a bit uneasy about moving
forward in case it starts acting up again, but it's been working now for over
an hour with lots of page refreshes and both of us hitting it at the same time.
Go figure.

[andiva]

So glad to hear KSmith's eval on the need to convert Access to SQL - this will
be done ASAP. Having the same problem with timed-out error message.

In the meantime, what can be done withing CFAdmin to help the problem -
limiting the connections in the Datasource area - or threads? To how many?

We are using CFMX7 on a Win 2k3 server - very fast, plenty of memory, but
just a lot of hits on our poor access database, I think. It seems to "freeze'
CF completely when this happens, and we have to re-boot the entire web server
each time.

Is there a way to restart CF without re-booting? We've tried stopping and
re-starting CF in the services area, but it didn't work.

I'd appreciate any advice!

[Unregistered]

I am expericeing the same issue using ColdFusion MX 7 and Access 2007. I know Access can only handle a theoretical maximum of 255 simultaneous connections, but here are a couple things to consider.

First, in my situation, I am having this problem on test server where I am the only connection. This cannot be be a problem of too many connections because there is only one connection.

Second, the operative word is "simultaneous." In an Access desktop application, the front end maintains a constant connection with the backend so you are limited to 255 connections (if you can get that many). However when using a Web front end, the connection is held only long enough to make the transaction - in my case about 0.25 seconds. At the rate I should be able to handle over 61,000 requests per minute. And yet, as the only user on the sytem I am receiving "too many client tasks."