I am using ajax to run a django function. In this function, I connect to the database and run a sql statement, the result of which is saved to a csv file. This sql takes a long time to run at times, and I would like to be able to interrupt this function on demand. Is it possible? Can I get the id of the running process or request and use it to kill it?
Related
I am making a Django Rest framework based server and in one of the request, I get an audio file from front-end, on which I need to run some ML based algorithm(I have script for same) and respond back to user with the result. Problem is that this request might take 5-10 seconds to execute. I am trying to understand following things:
Will Celery help me reduce the workload on server, as in any case I need to wait for the result of the ML Algo and respond back to user.
Should I create a different server to handle this type of request? Will that be a better approach?
Also, is my flow of doing things correct. First, Upload the file to some cloud platform for storage and serialize the instance to get the url of file. Second run the script using celery and wait for the result. Third, Respond back with the result.
Thanks for helping.
Coldfusion 2016
Microsoft Server 2012
Oracle 12
ODBC connection
I turned on profiling and monitoring and now I can see that there are requests that are stuck and cannot be terminated by the CF monitor; Some are over 200k seconds.
I know I can increase the number of simultaneous requests but I want to solve the underlying problem. As I read the stack traces of these “zombie requests” they are getting stuck on and some are in but some are not. I ran the query in my oracle client and they resolve instantly.
Is there a way to terminate these requests or prevent this from happening at all?
EDIT: The server monitor does not treat these requests as slow or hung, the alerts are not triggering for any of these. Honestly, they should have be going off constantly considering how many of these there are.
Also, the execution time is a mere .003 seconds so what happened? Why doesn't ColdFusion know this?
An example of a "zombie"
The active query that is stuck
We have a similar situation with a different database engine - redbrick, which runs on a unix server. We solved it as follows.
We set up a cron job on the database server to run every 5 minutes. This job uses a combination of unix and awk commands.
This job runs a query against the system table that looks for queries that have been running for more than 120 seconds, where the database account is the one used by ColdFusion. Records are outputted to a file. Something like this:
print "alter system cancel user command userName process " $1 ";"
$1 comes from the query and is the process Id we want to stop.
Then we run the file, which executes all those alter system commands.
With a different database engine, and possible different OS for the database server, the details would be different, but the approach should work.
Edit Starts Here
To prevent recurrence, look at the pages that call the ones with the long running queries. If impatient users are able to repeatedly click something because nothing is happening, do something about that. You can use javascript to make the link/button go away. Alternatively, you can go to an intermediate page with a display for the user and something that carries them through to the real page.
If I submit a series of SQL statements (each with GO in sqlcmd) that I want to make an reasonable attempt to run on an Azure SQL Data Warehouse, I've found in sqlcmd how to ignore errors. But I've seen if I want to abort a statement in that sequence of statements with:
KILL "SIDxxxxxxx";
The whole session ends:
Msg 111202, Level 16, State 1, Server adws_database, Line 1
111202;Query QIDyyyyyyyyyy has been cancelled.
Is there a way to not end a query session in Azure SQL Data Warehouse? Similar to how postgres's
pg_cancel_backend()
works?
In postgres the
pg_terminate_backed(<pid>)
seems to be working similarly to the ADW
KILL 'SIDxxxx'
command.
Yes, a client can cancel a running request without aborting the whole session. In SSMS this is what the red square does during query execution.
Sqlcmd doesn't expose any way to cancel a running request, though. Other client interfaces do, like the .NET SqlClient you can use SqlCommand.Cancel()
David
I have simple bpl process with 3 invokes in loop. One of instances hang without any visible reason. So process is in active state but it is not executing any longer. Last logged activity is call to invoke. I search database and find out that both request and response are present in table ode_message and they looks correctly. But output variable from invoke in table ode_xml_data is not filled. There is no logs in bps from time when message arrived. Is any way to find out what happen wrong?
I'm try to use Wso2 BPS 2.1.2
I'm working on a script that creates a MySQL dump via <cfexecute> and then FTPs the SQL script to another server. I've resorted to checking once per second to see if the filesize has changed, and if it has not changed within the past five seconds I assume it has completed.
This is fine for the current application, but eventually I would like to be able to import the SQL script on the second server and provide some sort of notification that it has completed.
Is there some way to track the status of a running process?
If not, is there a way to accomplish a full DB export and import via ColdFusion alone?
Actually you may not realize it, but when you call <cfexecute> without passing a timeout attribute it defaults to '0' timeout. And if you read the docs on <cfexecute> you'd see:
If the value is 0:
ColdFusion starts a process and returns immediately. ColdFusion may
return control to the calling page
before any program output displays. To
ensure that program output displays,
set the value to 2 or higher.
So I would suggest passing a higher value for timeout which will cause ColdFusion to wait for mysqldump to complete before moving on.
Reference
Check out Event Gateways[1] for one way to deal with asynchronous operations. There's a Directory Watcher gateway that comes with CF as an example.[2]
Barring that, create some sort of batch processing facility using CF Scheduled Tasks. Add the job to a database table and have a scheduled task periodically pull jobs out of the table and execute them, reporting on the result. A second scheduled task can detect that the first completed and carry out the next step of the process.
[1] http://help.adobe.com/en_US/ColdFusion/9.0/CFMLRef/WSc3ff6d0ea77859461172e0811cbec214e3-7fa7.html
[2] http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec22c24-77f7.html