We are using SQL Server 2012 Enterprise edition.
Normally we get hardly any blocked processes, but last weekend we experienced very unusual situation. Within 2 hours we got more "blocked process" alerts than we did in the last year together. There were a few hundred alerts within this time. Then suddenly without any interference from anyone everything went back to norm and we didn't get any blocked processes ever since. I want to prevent this situation from occurring again.
I am well aware how to find what can be causing blocking at present, but I have very little idea how to find what caused the block in the past, which is currently resolved.
I checked error logs in SQL Server Management Studio, but there is nothing there under the date when blocking occurred. There is also nothing unusual in the Windows event viewer. Where else should I check?
Could you please help?
From what you describe, I'm not too sure you will actually find the cause of the previously blocking processes if you did not actively setup tracing i.e. have your blocked process threshold set and configured with an alert to provide said trace information. The situation you described is interesting and definitely worth monitoring.
Here is an article on blocked process threshold configuration in SQL Server and a link through to Alerts configuration.
Hope this helps
Related
We have a transaction that has a fair number of updates and inserts that run inside it as sent by our server-side code. We've run into an issue where all work in the transaction up to a given point is rolled back, and then later updates/inserts are run and end up being committed when the transaction is closed.
We narrowed it down to a bit of code where it would always happen and pulled that code out. Then the same behavior started happening elsewhere in the transaction. Nothing in our code is telling the transaction to roll back, and we haven't changed our code on our prod servers for quite a while before it started happening.
We finally restarted our prod db server and the problem went away, for a little while. Then it started happening again, and happened consistently after that.
We're on SQL Server 2016 and our web server is running ColdFusion 11 hotfix 18. Queries are being issued via <cfquery> inside a <cftransaction>.
Has anyone run into anything like this or have any way to diagnose the issue?
Update w/ more info: Apparently SQL Server was processing hardly any updates. We finally discovered that a log file was out of space. This usually will produce notifications/errors that this has happened, but this time it didn't for some reason. I realize this question is probably not the very highest quality, but in hopes that anyone who may run into this will find this and gain some benefit, I'm leaving it here.
Sometimes a server where an instance of SQL Server is running needs a restart. This occurs typically when the memory is fully used and rebooting somehow drastically solves the issue. The reason of full memory can be difficult to pinpoint (may be an old service who is running with poor garbage collection or other similar issues, or simply windows OS builtin problems, ...).
When the server is in such instable state a client server application runs into troubles because simple queries fail because SQL Server is not able to handle even simple queries and error messages are returned.
What I'd like to achieve is, just after connection is estabilished, ask the server "do you feel good?".
Is there a way to perform this in T-SQL?
Somehow my desired logic is:
connect
ask the server "do you feel good" ("EXEC sp_doyoufeelgood")
if it feels good continue
else close the application and inform the user "the server is encountering some problems, please contact your sysadmin"
Is there a reliable way to check for a SQL Server instance status?
Take a look at this one could be interesting:
sp_Blitz® http://www.brentozar.com/blitz/
I'm a new "accidental" DBA and I'm currently trying to resolve a lockup caused by a trigger I created on a production database supporting a front end application.
I created a trigger, and then I decided I'd be best off creating a job to do the work instead, so tried to delete the trigger in object explorer. The delete failed with the message:
An exception occurred while executing a Transact-SQL statement or batch.
Lock request time out period exceeded.
I then tried to manually drop it and it failed at 0%, 0s left to go. I checked for the longest running transaction and then tried to kill the process in activity monitor. Since then the process has been stuck on "Task State:RUNNING and Command:KILLED/ROLLBACK". After some googling it sounds like I have two options.
Option 1: Restart DTC on the SQL server.... didn't work, still stuck.
Option 2: Restart the SQL service. Uh-oh.
This is the first time I've ever had to do anything like this and I'm pretty nervous being the only SQL guy in the office. Please can anyone let me know what the potential implications of restarting the service are, in terms of data loss and impact to front end users? Am I better off waiting to restart after business hours?
Thanks, and apologies if I've asked this question badly, first time for everything.
Cheers
Wait. It's rolling back and has to finish the rollback. Don't restart SQL, that will just result in the rollback continuing after the restart, possibly with the database offline.
If this is a production system and you do bounce the database, all users of your user interface will get weird and wonderful errors. Unless your application can handle it, your users will have a bad experience and then you will start getting phone calls from the boss....
As a side note, check for locking\blocking processes. The message in the question "Lock request time out period exceeded. " seems to suggest there is locking/blocking happening.
I have a web application that occasionally will throw this error….
Exception message: Timeout expired.
The timeout period elapsed prior to
completion of the operation or the
server is not responding.
When I does I am unable to connect to SQL server, even through management studio, it’s says the server timed out and cannot connect.
As soon as I reset iis, it comes back instantly. So this obviously means it’s something in my code that’s causing this. I have an MVC site that uses Linq to SQL and SQL cache dependency with service broker enabled.
I have used the using statement thoroughly throughout the code, so im sure it’s not leaky connections. Reading through the server logs makes things more confusing as there are so many information and warning events, im not a sys admin so it’s hard to know what’s going on.
It begins with me getting an ASP.net 4.xxxxx Event ID 1309 Exception message: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. error
I think I got round it last time on my previous server by restating IIS when ever this error popped up, this is something I don’t want to resort to on this new server.
So my question is, what steps can I take to try and reduce but ideally eliminate this timeout error ?
Any help is most appreciated
Truegilly
This type of problem usually boils down to one of two things. Either you are not disposing of your connections properly or you have a number of heavy queries that are completely taking over your database server.
If you don't dispose of the connections properly then IIS will happily keep them around until garbage collection runs and/or they timeout. If you have a very lightly trafficked site then you won't see the problem.
However, once traffic reaches the point where the number of connections hanging around exceeds the number of times you are trying to make a connection to the database server.. well, you are going to start seeing one of a couple possible errors. Timeout expired is one. The exact error is going to depend on which part is falling over: the connection pool, the sql server itself, etc.
The fix you commented on is a temporary solution. As your traffic continues to increase (good problem to have) then other areas of your code are going to cause the issue to come up again.
I'm currently experiencing some problems on my DotNetNuke SQL Server 2005 Express site on Win2k8 Server. It runs smoothly for most of the time. However, occasionally (order once or twice an hour) it runs very slowly indeed - from a user perspective it's almost like there's a deadlock of some description when this occurs.
To try to work out what the problem is I've run SQL Profiler against the SQL Express database.
Looking at the results, some specific questions I have are:
The SQL trace shows an Audit Logon and Audit Logoff for every RPC:Completed - does this mean Connection Pooling isn't working?
When I look in Performance Monitor at ".NET CLR Data", then none of the "SQL client" counters have any instances - is this just a SQL Express lack-of-functionality problem or does it suggest I have something misconfigured?
The queries running when the slowness occur don't yet seem unusual - they run fast at other times. What other perfmon counters or other trace/log files can you suggest as useful tools for my further investigation.
Jumping straight to Profiler is probably the wrong first step. First, try checking the Perfmon stats on the server. I've got a tutorial online here:
http://www.brentozar.com/perfmon
Start capturing those metrics, and then after it's experienced one of those slowdowns, stop the collection. Look at the performance metrics around that time, and the bottleneck will show up. If you want to send me the csv output from Perfmon at brento#brentozar.com I can give you some insight as to what's going on.
You might still need to run Profiler afterwards, but I'd rule out the OS and hardware first. Also, just a thought - have you checked the server's System and Application event logs to make sure nothing's happening during those times? I've seen instances where, say, the antivirus client downloads new patches too often, and does a light scan after each update.
My spidey sense tells me that you may have SQL Server blocking issues. Read this article to help you monitor blocking on your server to check if its the cause.
If you think the issues may be performance related and want to see what your hardware bottleneck is, then you should gather some cpu, disk and memory stats using perfmon and then co-relate them with your profiler trace to see if the slow response is related.
no
nothing wrong with that...it shows that you're not using the .NET functionality embed in SQL Server.
You can check http://www.xsqlsoftware.com/Product/xSQL_Profiler.aspx for more detailed analysis of profiler trace. It has reports that show top queries by time or CPU (Not one single query, but sum of all execution of a single query).
Some other things to check:
Make sure your datafiles or log files
are not auto-extending.
Make sure your anti-virus is set to
ignore your sql data and log
files.
When looking at the profiler output, be sure the check the queries that finished just prior to your targets,
they could've been blocking.
Make sure you've turned off Auto-close on the database; re-opening after closing takes some
time.