dotnet/aspnetcore

SQL Server Distributed Cache Extensions suffering significant performance issues

Open

#28,366 opened on Nov 19, 2020

View on GitHub
 (5 comments) (0 reactions) (0 assignees)C# (10,653 forks)batch import
area-middlewarefeature-cachinghelp wanted

Repository metrics

Stars
 (37,933 stars)
PR merge metrics
 (Avg merge 16d 9h) (258 merged PRs in 30d)

Description

Describe the bug

Serious performance issues when reading binary values, when using SQL Server Distributed Cache extension.

To Reproduce

Using SQL Server Distributed Cache, persist a value with an arbitrary value of 15MB. Access the data using the async read operations. Note this takes approximately 15 seconds in our environment.

Expected behavior

This should take milliseconds.

Additional context

I suspect this is caused by an open SQL Client bug mentioned below. Can you please verify if this is the case? Is there a work-around that can be implemented in DatabaseOperations until this is resolved?

https://github.com/dotnet/extensions/blob/master/src/Caching/SqlServer/src/DatabaseOperations.cs, line 229 value = reader.GetFieldValue<byte[]>(Columns.Indexes.CacheItemValueIndex);

Reading binary data asynchronously is extremely slow https://github.com/dotnet/SqlClient/issues/593

It looks like the SqlClient team are suggesting people use the StreamAsync operation as a work-around?

One reasonably successful work-around we have tried is to increase the TDS Packet Size up to 32,767. What are your thoughts on this?

Contributor guide

Research direction
Review DatabaseOperations.cs line 229 where GetFieldValue<byte[]> is used and consider switching to ReadStreamAsync as suggested by the SqlClient team. Implement the streaming approach to improve performance.
Tech stack
csharp
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75