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SQL Server ODBC + eventlet non-blocking IO hangs and weird behavior RRS feed

  • Question

  • Hi, this new question is made in reference to (https://social.technet.microsoft.com/Forums/sqlserver/en-US/9e5b6d96-f9a2-4249-bd39-7f997165c502/sql-server-odbc-experimenting-with-eventlet-nonblocking-io-results-in-segfaults-sometimes?forum=sqldataaccess)

    It didn't receive any replies, but the issue of segfaults seems to have been fixed as I'm unable to reproduce the problem as of late. So thanks very much if some work was done in regard to the segfault.

    The problem of async IO communication with SQL Server doesn't seem to be solved though.

    Using the test app found here (https://github.com/bpaterni/flask-app-simple-blocking-eventlet)

    If no changes are made to the way connections are setup, the app seems to be able to handle a small number of requests (< 15) at the same time alright, but if the number of requests ventures beyond that, the app will hang seemingly indefinitely until it's interrupted (Ctrl-C). From there, one or a few requests throw an exception (presumably the ones being worked on at the time of the interrupt?), and the app continues processing requests that weren't subject to the hang or the interrupt.

    If on the other hand - on the suggestion of an eventlet developer (https://github.com/eventlet/eventlet/issues/538) - I switch to using a Tpooled connection pool creator, the app begins to behave similar to expectations for an async app. But if the max number of pool slots is arbitrarily high (~35) or unlimited, a hang sill occurs if load exceeds this threshold.

    Is it possible for the ODBC driver to be augmented in such a way to not hang in the cases described above, and possibly behave more asynchronously without explicitly telling sqlalchemy to use a Tpooled connection pool?

    Thank you very much for your help! :)

    Wednesday, November 13, 2019 6:12 AM

All replies

  • Hi bpaterni,

    Sorry for my poor understanding .Do you want to make some Suggestions about the product itself?

    If so , I advise you to post this issue in this website to check.  https://feedback.azure.com/forums/908035-sql-server Your feedback enables Microsoft to offer the best software and deliver superior services. 

    Best Regards,

    Rachel



    MSDN Community Support
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    Thursday, November 14, 2019 9:07 AM
  • Hi Rachel,

    My intention was to report an issue I've been seeing with the SQL Server ODBC Driver in hopes that it would be resolved. It's not meant to be as much a suggestion, but rather a request for help, and for a possible fix to be implemented somewhere to resolve the issue. I'm not certain if the source of the problem is the SQL Server ODBC Driver or the code that calls it after exploring the issue first with Flask-SocketIO, and later eventlet. So after browsing the official material on the ODBC Driver, it seems like this forum would be the best place to make such a request. If not here, please let me know the appropriate place to pose a question regarding the development  and/or support of the SQL Server ODBC Driver (linux in particular). I think someone more familiar than me with the internal workings of the ODBC Driver would be better suited to investigate this issue further.

    Thanks for you help! :)


    • Edited by bpaterni Friday, November 15, 2019 3:03 AM
    Friday, November 15, 2019 3:03 AM
  • Hi bpaterni, 

    Thank you for your issue .

    In this forum , we provide some service of SQL Server Data Access. But I am not sure how to reappear your issue without your actual environment . 

    Maybe you can ask professional engineer for help, and they will deal with your problem separately and confidentially. They can test remotely from your actual environment. https://support.microsoft.com/en-us/assistedsupportproducts

    Also, if you actually think it is an unknown issue, please post this issue in this website to check if it is really a problems to be discovered.  https://feedback.azure.com/forums/908035-sql-server  Your feedback enables Microsoft to offer the best software and deliver superior services. 

    Best Regards,

    Rachel 


    MSDN Community Support
    Please remember to click "Mark as Answer" the responses that resolved your issue, and to click "Unmark as Answer" if not. This can be beneficial to other community members reading this thread. If you have any compliments or complaints to MSDN Support, feel free to contact MSDNFSF@microsoft.com.

    Friday, November 15, 2019 7:11 AM
  • Hi Rachel,

    Thanks for your response. The issue I've been seeing _should_ be able to be reproduced using the test app linked

    https://github.com/bpaterni/flask-app-simple-blocking-eventlet

    Will certainly investigate the other paths for assistance you've mentioned as well.

    Thanks!

    Friday, November 15, 2019 6:51 PM
  • Hi bpaterni, 

    Sorry for my poor knowledge. I am not familiar with your current language. So I might  be hard to solve this problem .I will advice you to ask professional engineer for help, and they will deal with your problem separately and confidentially. They can test remotely from your actual environment. 

    Also you can wait others help in this forum .

    Best Regards,

    Rachel 


    MSDN Community Support
    Please remember to click "Mark as Answer" the responses that resolved your issue, and to click "Unmark as Answer" if not. This can be beneficial to other community members reading this thread. If you have any compliments or complaints to MSDN Support, feel free to contact MSDNFSF@microsoft.com.

    Monday, November 18, 2019 9:18 AM