Ethan 11481d7bed perf(coderd/chatd): reduce lock contention in instruction cache and persistStep (#23144) ...

## Summary

Two targeted performance improvements to the chatd server, identified
through benchmarking.

### 1. RWMutex for instruction cache

The instruction cache is read on every chat turn to fetch the home
instruction file for a workspace agent. Writes only occur on cache
misses (once per agent per 5-minute TTL window), making the access
pattern ~90%+ reads.

Switching from `sync.Mutex` to `sync.RWMutex` and using
`RLock`/`RUnlock` on the read path allows concurrent readers instead of
serializing them.

**Benchmark (200 concurrent chats):**
| | ns/op |
|---|---|
| Mutex | 108 |
| RWMutex | 32 |
| **Speedup** | **3.4x** |

### 2. Hoist JSON marshaling out of persistStep transaction

`MarshalParts`, `PartFromContent`, `CalculateTotalCostMicros`, and the
`usageForCost` struct population are pure CPU work that ran inside the
`FOR UPDATE` transaction in `persistStep`. They have zero dependency on
the database transaction.

Moving all marshal and cost-calculation calls above `p.db.InTx()` means
the row lock is held only for `GetChatByIDForUpdate` +
`InsertChatMessage` calls.

**Benchmark (16 goroutines contending on same lock):**
| Tool calls | Inside lock | Outside lock | Speedup |
|---|---|---|---|
| 1 | 13,977 ns/op | 1,055 ns/op | 13x |
| 5 | 38,203 ns/op | 3,769 ns/op | 10x |
| 10 | 67,353 ns/op | 7,284 ns/op | 9x |
| 20 | 145,864 ns/op | 14,045 ns/op | 10x |

No behavioral changes in either commit.

2026-03-18 16:12:14 +11:00

..

agentapi

fix: prevent emitting build duration metric for devcontainer subagents (#22929)

2026-03-10 20:10:08 -05:00

agentmetrics

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

aibridge

feat: use coder specific header for aibridge authentication from AI proxy (#21590)

2026-01-21 19:06:19 +00:00

aiseats

feat: track ai seat usage (#22682)

2026-03-16 12:36:26 -05:00

apidoc

feat: add support for creating service accounts (#23140)

2026-03-17 15:36:20 -06:00

apikey

fix: initialize API key LastUsed to Unix epoch instead of zero time (#22327)

2026-03-02 16:02:01 +01:00

appearance

…

audit

chore: add audit log entry when ai seat is consumed (#22683)

2026-03-16 15:30:25 -05:00

autobuild

fix: use "idle timeout" as task auto-pause reason (#22287)

2026-02-24 16:45:56 +00:00

awsidentity

…

azureidentity

chore: update azure certs (#21265)

2025-12-15 13:44:44 -09:00

boundaryusage

fix: make boundary usage telemetry collection atomic (#21907)

2026-02-06 09:52:17 -07:00

cachecompress

fix(site): avoid duplicating bin download headers (#22981)

2026-03-13 00:22:55 +11:00

chatd

perf(coderd/chatd): reduce lock contention in instruction cache and persistStep (#23144)

2026-03-18 16:12:14 +11:00

coderdtest

feat: add service_accounts workspace sharing mode (#23093)

2026-03-17 12:16:43 -07:00

connectionlog

fix: avoid connection logging crashes in agent (#20307)

2025-10-16 01:56:43 +11:00

cryptokeys

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

database

feat: add support for creating service accounts (#23140)

2026-03-17 15:36:20 -06:00

devtunnel

chore: remove unnecessary loop variable captures (#22180)

2026-02-19 09:02:19 +00:00

dynamicparameters

chore(coderd/database): remove deprecated db2sdk.List(Lazy)? methods (#21902)

2026-02-03 17:52:07 +00:00

entitlements

feat: add Prometheus metrics for license warnings and errors (#21749)

2026-01-29 13:50:15 +01:00

externalauth

feat: add head_branch to pull request diff status (#23076)

2026-03-14 17:24:19 +00:00

files

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

gitsshkey

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

gitsync

fix: use SQL-level auth filtering for chat listing (#23159)

2026-03-17 12:46:24 -04:00

healthcheck

refactor(healthcheck): reduce test boilerplate with healthyChecker helper (#23028)

2026-03-13 10:40:57 +00:00

httpapi

fix(coderd): downgrade heartbeat ping errors for closed connections to debug (#23025)

2026-03-13 10:38:39 +00:00

httpmw

fix: rate limit by user instead of IP for authenticated requests (#22049)

2026-03-09 13:54:31 +01:00

idpsync

test: remove unnecessary dbauthz.AsSystemRestricted calls in tests (#22663)

2026-03-05 20:29:49 +00:00

jobreaper

fix: exclude provisioner_state from workspace_build_with_user view (#22159)

2026-02-23 22:46:17 -06:00

jwtutils

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

mcp

fix(coderd): harden OAuth2 provider security (#22194)

2026-02-23 12:18:44 +01:00

metricscache

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

notifications

test: remove unnecessary dbauthz.AsSystemRestricted calls in tests (#22663)

2026-03-05 20:29:49 +00:00

oauth2provider

fix(coderd): harden OAuth2 provider security (#22194)

2026-02-23 12:18:44 +01:00

oauthpki

fix(coderd): support string type for oidc response's expires_in json property (#20152)

2025-10-15 17:37:37 +00:00

portsharing

…

pproflabel

chore: add usage tracking package (#19095)

2025-08-16 01:31:00 +10:00

prebuilds

chore: remove unnecessary loop variable captures (#22180)

2026-02-19 09:02:19 +00:00

prometheusmetrics

test: remove unnecessary dbauthz.AsSystemRestricted calls in tests (#22663)

2026-03-05 20:29:49 +00:00

promoauth

fix!: remove deprecated prometheus metrics (#21788)

2026-01-30 13:30:06 +01:00

provisionerdserver

feat: track ai seat usage (#22682)

2026-03-16 12:36:26 -05:00

provisionerkey

chore!: ensure consistent secret token generation and hashing (#20388)

2025-10-23 15:38:49 -05:00

proxyhealth

feat: add csp headers for embedded apps (#18374)

2025-06-17 09:00:32 -08:00

pubsub

fix(chat): fix streaming bugs in edit notifications, persist race, and frontend reconnect (#22737)

2026-03-06 15:11:05 -08:00

rbac

feat: add service_accounts workspace sharing mode (#23093)

2026-03-17 12:16:43 -07:00

render

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

runtimeconfig

chore(coderd/runtimeconfig): remove dbmem from tests (#18790)

2025-07-08 14:31:05 +00:00

schedule

chore: remove unnecessary loop variable captures (#22180)

2026-02-19 09:02:19 +00:00

searchquery

fix: use SQL-level auth filtering for chat listing (#23159)

2026-03-17 12:46:24 -04:00

taskname

fix(coderd): strip markdown code fences from Anthropic task name responses (#23024)

2026-03-13 17:35:26 +00:00

telemetry

feat: add telemetry for task lifecycle events (#21922)

2026-02-24 17:04:42 +00:00

testdata

feat: add flag to disable template insights (#20940)

2025-12-14 03:00:03 +00:00

tracing

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

updatecheck

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

usage

chore: add unknown usage event type error (#19436)

2025-08-22 16:32:35 +10:00

userpassword

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

util

feat(namesgenerator): expand auto-generated name digit suffix to 00-99 (#22665)

2026-03-06 15:09:58 +01:00

webpush

perf(coderd): reduce duplicated reads in push and webpush paths (#23115)

2026-03-17 13:50:47 +11:00

workspaceapps

fix(workspaceapps): use fresh context in LastUsedAt assertions (#22863)

2026-03-10 16:53:28 +00:00

workspacestats

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

wsbuilder

fix: mark presets as validation_failed to prevent endless prebuild retries (#22085)

2026-02-27 14:26:48 +00:00

wspubsub

feat: add WatchAllWorkspaceBuilds endpoint for autostart scaletests (#22057)

2026-03-13 20:37:41 -07:00

activitybump_test.go

test: add testutil.WaitBuffer and replace time.Sleep in tests (#22922)

2026-03-12 18:07:52 +02:00

aitasks_internal_test.go

fix: set codersdk.Task current_state during task initialization (#20692)

2025-11-17 13:24:12 +00:00

aitasks_test.go

test(coderd): remove provisioner daemon from SendToNonActiveStates test (#22298)

2026-02-25 13:14:32 +02:00

aitasks.go

feat: make coder task send resume paused tasks (#22203)

2026-03-07 01:36:03 +00:00

apikey_scopes_validation_test.go

feat: add multi-scope support to API keys (#19917)

2025-09-26 11:56:34 +02:00

apikey_test.go

fix(coderd): use dbtime.Now() instead of time.Now() in test assertions against DB timestamps (#22685)

2026-03-06 09:14:11 +00:00

apikey.go

feat(coderd): filter expired API tokens server-side (#22263)

2026-02-24 15:27:03 +00:00

apiroot.go

…

audit_internal_test.go

…

audit_test.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

audit.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

authorize_test.go

feat: add an organization member permission level (#19953)

2025-10-27 17:14:16 -06:00

authorize.go

feat: add experimental agents support (#22290)

2026-02-27 16:50:56 +00:00

chats_test.go

refactor: consolidate experimental chats API types (#23143)

2026-03-17 14:31:11 +00:00

chats.go

fix: use SQL-level auth filtering for chat listing (#23159)

2026-03-17 12:46:24 -04:00

client_test.go

…

coderd_internal_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

coderd_test.go

fix: rate limit by user instead of IP for authenticated requests (#22049)

2026-03-09 13:54:31 +01:00

coderd.go

refactor: consolidate experimental chats API types (#23143)

2026-03-17 14:31:11 +00:00

csp.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

debug_test.go

feat(coderd): add consolidated /debug/profile endpoint for pprof collection (#22892)

2026-03-13 14:09:39 +00:00

debug.go

feat(coderd): add consolidated /debug/profile endpoint for pprof collection (#22892)

2026-03-13 14:09:39 +00:00

deployment_test.go

…

deployment.go

chore: remove chats experiment (#18535)

2025-06-25 13:03:32 +00:00

deprecated.go

…

experiments_test.go

chore: revert dynamic params as a safe experiment (#17510)

2025-04-22 16:21:15 +00:00

experiments.go

fix: do not warn on valid known experiments (#18514)

2025-06-24 09:14:41 +01:00

externalauth_test.go

feat(coderd/rbac): make organization-member a per-org system custom role (#21359)

2026-01-12 18:19:19 -08:00

externalauth.go

feat!: support PKCE in the oauth2 client's auth/exchange flow (#21215)

2025-12-15 17:41:47 +00:00

files_test.go

ci: improve 'tfail in goroutine' ruleguard rule (#19682)

2025-09-04 14:28:29 +10:00

files.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

gitsshkey_test.go

chore: distinct operations for provisioner's 'parse', 'init', 'plan', 'apply', 'graph' (#21064)

2025-12-15 11:26:41 -06:00

gitsshkey.go

feat: add API key scope to restrict access to user data (#17692)

2025-05-15 15:32:52 +01:00

inboxnotifications_internal_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

inboxnotifications_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

inboxnotifications.go

fix(coderd): ensure inbox WebSocket is closed when client disconnects (#21652)

2026-01-26 09:24:45 +00:00

initscript_test.go

feat(coderd): add support for external agents to API's and provisioner (#19286)

2025-08-19 10:41:33 +02:00

initscript.go

feat(coderd): add support for external agents to API's and provisioner (#19286)

2025-08-19 10:41:33 +02:00

insights_internal_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

insights_test.go

fix(coderd): fix flaky TestGetUserStatusCounts timezone boundary (#22639)

2026-03-04 18:01:56 -08:00

insights.go

fix: user status change chart accommodates DST (#22191)

2026-03-04 12:54:39 +02:00

latencycheck.go

…

mcp_http.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

members_test.go

feat: add endpoint to fetch singular org member (#21732)

2026-02-03 12:48:25 -06:00

members.go

fix: prevent ui error when last org member is removed (#22975)

2026-03-13 08:15:37 +11:00

notifications_test.go

chore: return 404, not 400 if missing or authz deny (#22069)

2026-02-13 08:19:07 -06:00

notifications.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

oauth2_error_compliance_test.go

refactor: add RFC-compliant enum types and use SDK as source of truth (#21468)

2026-01-15 12:41:28 +03:00

oauth2_metadata_test.go

refactor: add RFC-compliant enum types and use SDK as source of truth (#21468)

2026-01-15 12:41:28 +03:00

oauth2_metadata_validation_test.go

refactor: add RFC-compliant enum types and use SDK as source of truth (#21468)

2026-01-15 12:41:28 +03:00

oauth2_security_test.go

feat: implement OAuth2 dynamic client registration (RFC 7591/7592) (#18645)

2025-07-03 18:33:47 +02:00

oauth2_test.go

fix(coderd): use dbtime.Now() instead of time.Now() in test assertions against DB timestamps (#22685)

2026-03-06 09:14:11 +00:00

oauth2.go

feat: implement oauth2 RFC 7009 token revocation endpoint (#20362)

2025-10-22 15:18:42 -05:00

organizations_test.go

…

organizations.go

chore(coderd/database): remove deprecated db2sdk.List(Lazy)? methods (#21902)

2026-02-03 17:52:07 +00:00

pagination_test.go

feat: add connectionlogs API (#18628)

2025-07-15 14:55:34 +10:00

pagination.go

feat: add connectionlogs API (#18628)

2025-07-15 14:55:34 +10:00

parameters_test.go

feat: archive modules in size order until limit is hit (#21773)

2026-02-02 09:03:18 -06:00

parameters.go

chore(coderd/database): remove deprecated db2sdk.List(Lazy)? methods (#21902)

2026-02-03 17:52:07 +00:00

presets_test.go

chore: remove unnecessary loop variable captures (#22180)

2026-02-19 09:02:19 +00:00

presets.go

feat: support icon and description in preset (#18977)

2025-07-28 15:02:26 +01:00

provisionerdaemons_test.go

feat: add filtering options to provisioners list (#19378)

2025-08-21 16:03:34 -04:00

provisionerdaemons.go

chore(coderd/database): remove deprecated db2sdk.List(Lazy)? methods (#21902)

2026-02-03 17:52:07 +00:00

provisionerjobs_internal_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

provisionerjobs_test.go

test: reduce unnecessary sleep durations in tests (#22552)

2026-03-03 10:19:00 -05:00

provisionerjobs.go

chore(coderd/database): remove deprecated db2sdk.List(Lazy)? methods (#21902)

2026-02-03 17:52:07 +00:00

roles_test.go

…

roles.go

feat(coderd/rbac): make organization-member a per-org system custom role (#21359)

2026-01-12 18:19:19 -08:00

scopes_catalog_api_test.go

feat: add external API key scopes (#19916)

2025-09-26 11:43:32 +02:00

scopes_catalog.go

feat: add external API key scopes (#19916)

2025-09-26 11:43:32 +02:00

tailnet_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

tailnet.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

templates_test.go

fix: hide "Create Workspace" button for deleted templates (#22092)

2026-02-13 19:44:50 -05:00

templates.go

fix: hide "Create Workspace" button for deleted templates (#22092)

2026-02-13 19:44:50 -05:00

templateversions_test.go

feat: validate prebuild presets using dynamic parameter validation (#21858)

2026-03-03 16:50:18 +00:00

templateversions.go

feat: validate prebuild presets using dynamic parameter validation (#21858)

2026-03-03 16:50:18 +00:00

updatecheck_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

updatecheck.go

…

userauth_test.go

fix(coderd): render HTML error page for OIDC email validation failures (#23059)

2026-03-16 11:56:59 -04:00

userauth.go

fix(coderd): render HTML error page for OIDC email validation failures (#23059)

2026-03-16 11:56:59 -04:00

users_test.go

feat: backend support for creating and storing service accounts (#22698)

2026-03-11 10:19:08 -07:00

users.go

feat: backend support for creating and storing service accounts (#22698)

2026-03-11 10:19:08 -07:00

webpush_test.go

perf(coderd): reduce duplicated reads in push and webpush paths (#23115)

2026-03-17 13:50:47 +11:00

webpush.go

perf(coderd): reduce duplicated reads in push and webpush paths (#23115)

2026-03-17 13:50:47 +11:00

workspaceagentportshare_test.go

feat(coderd/rbac): make organization-member a per-org system custom role (#21359)

2026-01-12 18:19:19 -08:00

workspaceagentportshare.go

docs: fix swagger documentation for DELETE port share endpoint (#18426)

2025-06-18 14:07:53 +00:00

workspaceagents_internal_test.go

feat: agents git watch backend (#22565)

2026-03-06 10:47:55 +01:00

workspaceagents_test.go

fix(coderd): use dbtime.Now() for tailnet telemetry timestamps (#22861)

2026-03-09 20:37:05 +00:00

workspaceagents.go

feat(coderd): refactors github pr sync functionality (#22715)

2026-03-10 18:46:01 +00:00

workspaceagentsrpc_internal_test.go

test: use not before in TestAgentConnectionMonitor_* (#21332)

2025-12-22 10:21:39 +04:00

workspaceagentsrpc_test.go

test: add testutil.WaitBuffer and replace time.Sleep in tests (#22922)

2026-03-12 18:07:52 +02:00

workspaceagentsrpc.go

fix(coderd): add role param to agent RPC to prevent false connectivity (#22052)

2026-02-18 09:44:06 +01:00

workspaceapps_test.go

chore: remove unnecessary redeclarations in for loops (#18440)

2025-06-20 13:16:55 -06:00

workspaceapps.go

feat: add multi-scope support to API keys (#19917)

2025-09-26 11:56:34 +02:00

workspacebuilds_test.go

feat: add link for viewing raw build logs in workspace and template build jobs (#21727)

2026-02-03 09:45:23 +00:00

workspacebuilds.go

feat: add WatchAllWorkspaceBuilds endpoint for autostart scaletests (#22057)

2026-03-13 20:37:41 -07:00

workspaceproxies_test.go

…

workspaceproxies.go

…

workspaceresourceauth_test.go

chore: distinct operations for provisioner's 'parse', 'init', 'plan', 'apply', 'graph' (#21064)

2025-12-15 11:26:41 -06:00

workspaceresourceauth.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00

workspaces_test.go

feat: add WatchAllWorkspaceBuilds endpoint for autostart scaletests (#22057)

2026-03-13 20:37:41 -07:00

workspaces.go

feat: add service_accounts workspace sharing mode (#23093)

2026-03-17 12:16:43 -07:00

workspaceupdates_test.go

chore: update testutil chan helpers (#17408)

2025-04-16 10:37:09 -06:00

workspaceupdates.go

chore: arrange imports in a standard way (#21452)

2026-01-08 15:24:11 +04:00