Issue with SqlConnection.Open on netcore3 linux images

[adrian-lopez-softtek]

I am having an issue when trying to open a connection to our SQL Server 2016 SP1 CU7 server from latest (not sure if it happens with previous) netcore 3 preview 9. The code just hangs when calling Open (same result with OpenAsync) and doesn't continue. Tried with both Microsoft.Data.SqlClient and System.Data.SqlClient NuGet packages.

Same code works fine when executed in my windows laptop outside Docker. If I switch to netcore 2.2 it works fine inside docker (changing images as well).

I have created a small repo with a repro: https://github.com/adrian-lopez-softtek/NetCore3SqlOpenIssue/

Tried with both images (the commented ones in the Dockerfile) with same result.

Any help would be appreciated, as I'm creating a new project with version 3 and don't want to switch to 2.2 at this point, but if I'm not able to make it work I will probably have to.

Thanks!

[adrian-lopez-softtek]

I did one more test connecting to one a Azure SQL database, and with this one works fine. Our on premise server version is 13.0.4466.4 vs cloud 12.0.2000.8, in case this helps

[adrian-lopez-softtek]

Managed to get it working using preview 9 ubuntu images (3.0.100-preview9-disco & 3.0.0-preview9-disco). Not sure what happens with debian images, but they didn't work for me.

[vik-singh]

-disco resolved this for us with SQL Server 2014 and Linux containers - You are a lifesaver @adrian-lopez-softtek !

[adrian-lopez-softtek]

Just tested this with RC1 and new debian docker images and the issue is still there

[iinuwa]

I am having the same issue: program connects just fine from my laptop and hangs on.

In a tcpdump I can see that there is a TDS7 pre-login request and response being sent, but the connection hangs before the credentials are checked. (Tested by sending bad credentials to the server with the same result as the correct credentials.)

I can confirm that the Ubuntu image does connect.

[aidanjryan]

There are a few issues out there about hangs but this looks the freshest. We are seeing a deadlock between SNIMarsHandle and SNIMarsConnection. When we disable multiple active result sets on the connection string, the issue is gone.

snimarshandle handleack -- lock(this)
snimarsconn handlereceivingcomplete -- lock(this)

snimarsconn sendasync -- lock(this)
snimarshandle internalsendasync  -- lock (this)

[cheenamalhotra]

Hi @aidanjryan

As we have more MARS related issues reported and users have reported regressions that occurred in System.Data.SqlClient. Could you test this case with System.Data.SqlClient 4.6.1 and confirm if that was a working version? We're trying to reach the root cause of the problems.

[aidanjryan]

@cheenamalhotra we were using System.Data.SqlClient with the same connection string, same client code, with no issues until changing to .NET Core 3.0 preview 7. I assume that was System.Data.SqlClient 4.6.1.

[clane2812]

Hello - we ran in exactly the same issue with both SqlClient-Packages (System.Data + Microsoft.Data). When we used the original Microsoft baseimages for netcore 3.0 we had this issue. When we changed to Ubuntu 18.04 (3.0-bionic) everything worked fine - thanks to @adrian-lopez-softtek for this hint!

[gfzhang8]

I am not sure if it's the same issue, in my case, the first time after I deployed a simple dotnet core 3.0 web api to linux image, sqlconnection open failed or takes around 100 seconds to just open the connection, then the database connection works well and very fast, after around 5 or 10 minutes, again the sqlconnection.open takes 100 seconds every time unless I redeploy the web api again.
I tried sqlserver 2008 and 2016, also I tried dotnet core 2.1 and 3.0, also tried Sysyem.Data.Sqlclient and Microsoft.Data.SqlClient, also tried -bionic and -disco images, all the same issue.
Appreciate if anyone has some hints.
Thanks.

[aidanjryan]

@gfzhang8 Do you have MultipleActiveResultSets=True in your connection string? Disabling this resolved the hang for us.