Application Server Freezes when importing solutions

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Application Server Freezes when importing solutions

Postby francisco.garcia » Tue Jan 09, 2018 4:00 pm

We are running server version 8.2.2 release 3107 with Apache Tomcat/7.0.76 and JVM 1.8.0_51-b16, everything running on Centos 7.
The issue happens when importing solutions. With no apparent cause the server freezes when we try to import solutions.
This happens with big production servers (from 80 to 160 clients connected) and with small testing servers. It happens more often with the larger solutions.
Basicly, the solution starts to import and at one point it freezes. No more clients can connect to the server and the clients that are connected can not use the system whatever solution they are working on. We can access the Servoy Application Server, but only the Servoy Server Home (not Clients), and we also can access the Apache Tomcat Admin Page.
First we thougth that it was an out of memory problem but the issue happens also in big servers with a huge ammount of memory available.
We are kind of lost with this, so we would appreciate any suggestions.
For more information please tell.
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Re: Application Server Freezes when importing solutions

Postby patrick » Tue Jan 09, 2018 4:44 pm

It sounds very much like a DB deadlock. What database is holding the repository? SQL Server (seen that there a few times). Maybe you could check the DB using an admin tool to see if a request is blocked when that occurs? For SQL server it could help to set "Allow snapshot isolation" and "Is Read Committed Snapshot On" on the repository database to true.
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Re: Application Server Freezes when importing solutions

Postby francisco.garcia » Tue Jan 09, 2018 5:36 pm

Hi Patrick. We are using Oracle MySQL. So you say that it can be a request to the servoy_repository that blocks the uploading?
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Re: Application Server Freezes when importing solutions

Postby patrick » Tue Jan 09, 2018 6:57 pm

I have seen one query blocking another, but never used mySQL. I'm not familiar with mySQL, so I cannot tell you how / where you can see blocking requests, but maybe you know or can figure that out.

You say you can still access servoy-admin when it hangs. Can you try to produce a stackdump from there (Click on "Dump the current stack/systeminfo")? You can copy all the text in there in a text file and attach it here, then someone can have a look and maybe see what's hanging.
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Re: Application Server Freezes when importing solutions

Postby francisco.garcia » Tue Jan 09, 2018 7:15 pm

i attach the stackdump at the moment of freezing of a testing server that we have.
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stackdump.txt
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Re: Application Server Freezes when importing solutions

Postby jcompagner » Wed Jan 10, 2018 11:28 am

a deadlock seems to happen between ngclient startups and a import if those are happening at the same time
For now put your server in maintenance mode before doing an import.

i created a case: https://support.servoy.com/browse/SVY-12029
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Re: Application Server Freezes when importing solutions

Postby francisco.garcia » Wed Jan 10, 2018 1:17 pm

Thank you Johan.
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Re: Application Server Freezes when importing solutions

Postby francisco.garcia » Wed Jan 10, 2018 10:18 pm

Just to clarify, we try to do the import in manteinance mode and it still hangs the server.
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Re: Application Server Freezes when importing solutions

Postby jcompagner » Thu Jan 11, 2018 11:18 am

yes i see now it happens way before the check for maintenance mode.
the first hit to the index.html of a ngclient solution can already cause this
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