Suitable for distributed azure applications

[madelson]

Suitable for distributed azure applications

[madelson]

HI @filoe, thanks for your interest in the library.

Is this suitable for distributed azure applications?

The SqlDistributedLock class and related SQL-based classes are designed for use in distributed applications. These classes leverage a central SQLServer's native sp_getapplock mechanism to coordinate locking between application threads and processes hosted on different servers.

While I haven't personally used the library on Azure, I know that at least one other has done so successfully (see this issue). One peculiarity of SqlAzure is it's aggressive timing out of idle connections. To better support this, version 1.3 of the library added a special connection management strategy for Azure to keep connection alive while the lock is held.

What's about the performance of this library? Let's say compared to azure storage leases.

In my experience the performance is quite good. The actions to acquire and release a lock require one SQL query each which is typically very fast (unless, of course, it needs to wait to acquire a lock that someone else is holding). The library offers async acquire functions so that threads are not blocked while waiting for a lock.

That said, I haven't worked with Azure leases so I can't offer a direct comparison. If performance is a concern, I would recommend testing each approach under realistic workloads and levels of concurrency to see which one makes sense for your use-case.

[filoe]

Thanks for fast and detailed answer.
I've got no experience in the field of large business applications.
Do you know whether it still works if I use georeplication on azure for the database?
Is it still guaranteed that all instances (accross the world - accessing different instances of the database) are synchronized by the locking?

[madelson]

@filoe I don't have experience with Azure so I definitely can't say for sure. However, I think it's unlikely that locks would replicate. The nature of locking means that there must be realtime coordination between all parties involved; this doesn't work in an "eventually consistent" system. You'll have to try it and see!