Perf | Reuse XmlWriterSettings, eliminate MemoryCacheEntryOptions allocations #3791
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Lazily initialize these where the class might be used without needing to support XML.
Member
|
/azp run |
|
Azure Pipelines successfully started running 2 pipeline(s). |
| AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(ThreadRetryCacheTimeoutInMinutes) | ||
| }; | ||
| ThreadRetryCache.Set<string>(Thread.CurrentThread.ManagedThreadId.ToString(), retryThreadID, options); | ||
| ThreadRetryCache.Set<string>(Thread.CurrentThread.ManagedThreadId.ToString(), retryThreadID, absoluteExpirationRelativeToNow: TimeSpan.FromMinutes(10)); |
Member
There was a problem hiding this comment.
Continue to use constant for timeout
Contributor
Author
There was a problem hiding this comment.
Thanks - I've reintroduced the various constants in this comment and elsewhere.
Comment on lines
-21
to
-22
| // Cache timeout of 8 hours to be consistent with jwt validity. | ||
| private static int enclaveCacheTimeOutInHours = 8; |
Member
There was a problem hiding this comment.
Continue using constant (convert it to const instead)
| AbsoluteExpirationRelativeToNow = TimeSpan.FromDays(10) | ||
| }; | ||
| _cache.Set<bool>(cacheLookupKey, result, options); | ||
| _cache.Set<bool>(cacheLookupKey, result, absoluteExpirationRelativeToNow: TimeSpan.FromDays(10)); |
Member
There was a problem hiding this comment.
Introduce const for magic number
| AbsoluteExpirationRelativeToNow = TimeSpan.FromHours(10) | ||
| }; | ||
| _cache.Set<Dictionary<string, SqlCipherMetadata>>(cacheLookupKey, cipherMetadataDictionary, options); | ||
| TimeSpan expirationPeriod = TimeSpan.FromHours(10); |
Member
There was a problem hiding this comment.
Introduce const for magic number
| AbsoluteExpirationRelativeToNow = TimeSpan.FromDays(1) | ||
| }; | ||
| rootSigningCertificateCache.Set<X509Certificate2Collection>(attestationUrl, certificateCollection, options); | ||
| rootSigningCertificateCache.Set<X509Certificate2Collection>(attestationUrl, certificateCollection, absoluteExpirationRelativeToNow: TimeSpan.FromDays(1)); |
Member
There was a problem hiding this comment.
Introduce const for magic number
Contributor
There was a problem hiding this comment.
Pull request overview
This PR implements two memory optimization improvements: (1) reuses XmlWriterSettings objects via static fields instead of allocating them repeatedly, and (2) eliminates allocations of MemoryCacheEntryOptions objects by using the MemoryCache.Set overload that accepts expiration timespan directly.
- Caches
XmlWriterSettingsobjects in static fields with lazy initialization inTdsParser,ValueUtilsSmi, andSqlStreamingXml - Refactors all
MemoryCache.Setcalls to useabsoluteExpirationRelativeToNowparameter directly instead of creatingMemoryCacheEntryOptionsobjects - Improves code clarity by moving cache timeout comments closer to their usage points
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| VirtualSecureModeEnclaveProviderBase.cs | Eliminates MemoryCacheEntryOptions allocation by using direct parameter |
| TdsParser.cs | Adds static fields for async/sync XmlWriterSettings with lazy initialization |
| SqlSymmetricKeyCache.cs | Eliminates MemoryCacheEntryOptions allocation by using direct parameter |
| SqlStream.cs | Adds static readonly XmlWriterSettings field in SqlStreamingXml class |
| SqlQueryMetadataCache.cs | Eliminates MemoryCacheEntryOptions allocations and extracts expiration period to local variable for reuse |
| SignatureVerificationCache.cs | Eliminates MemoryCacheEntryOptions allocation by using direct parameter |
| ValueUtilsSmi.cs | Adds static field for XmlWriterSettings with lazy initialization |
| EnclaveSessionCache.cs | Eliminates MemoryCacheEntryOptions allocation and moves timeout comment inline |
| EnclaveProviderBase.cs | Eliminates MemoryCacheEntryOptions allocation and inlines constant value |
| AzureAttestationBasedEnclaveProvider.cs | Eliminates MemoryCacheEntryOptions allocation by using direct parameter |
Comments suppressed due to low confidence (2)
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs:12775
- Write to static field from instance method, property, or constructor.
? (s_asyncWriterSettings ??= new() { CloseOutput = false, ConformanceLevel = ConformanceLevel.Fragment, Async = true })
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs:12776
- Write to static field from instance method, property, or constructor.
: (s_syncWriterSettings ??= new() { CloseOutput = false, ConformanceLevel = ConformanceLevel.Fragment });
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
Outdated
Show resolved
Hide resolved
Introduce and reintroduce constants containing cache expiration periods
paulmedynski
requested changes
Nov 24, 2025
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/EnclaveSessionCache.cs
Outdated
Show resolved
Hide resolved
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/Server/ValueUtilsSmi.cs
Outdated
Show resolved
Hide resolved
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
Outdated
Show resolved
Hide resolved
Contributor
|
/azp run |
|
Azure Pipelines successfully started running 2 pipeline(s). |
Turn the lazy field initialisation into a property, and the TimeOutInX constants which were only used to create a TimeSpan into a static readonly TimeSpan.
Contributor
|
/azp run |
|
Azure Pipelines successfully started running 2 pipeline(s). |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
This is a minor set of improvements in memory usage which I noticed while looking at the XML access pathway and thinking about some of the layers of caching within SqlClient.
The first commit caches and reuses
XmlWriterSettingsobjects. As per the remarks in the documentation, these can be reused and so don't need to be allocated every time. I've promoted these to astatic readonlyfield in theSqlStreamingXmlclass because this is only used when reading XML data. The other places this is used areTdsParserandValueUtilsSmi, and these don't necessarily need to use XML functionality so I lazily allocate them on first use.In the second commit, we eliminate allocations of
MemoryCacheEntryOptionsobjects. These are essentially DTOs which are used to modify the expiration times of entries in various MemoryCaches. Rather than allocating a new object, we can use a different overload which accepts the expiration timespan directly.Issues
None.
Testing
Local tests of these pathways pass - could someone run CI please?