[performance] massively improved ActivityPub delivery worker efficiency (#2812)

* add delivery worker type that pulls from queue to httpclient package

* finish up some code commenting, bodge a vendored activity library change, integrate the deliverypool changes into transportcontroller

* hook up queue deletion logic

* support deleting queued http requests by target ID

* don't index APRequest by hostname in the queue

* use gorun

* use the original context's values when wrapping msg type as delivery{}

* actually log in the AP delivery worker ...

* add uncommitted changes

* use errors.AsV2()

* use errorsv2.AsV2()

* finish adding some code comments, add bad host handling to delivery workers

* slightly tweak deliveryworkerpool API, use advanced sender multiplier

* remove PopCtx() method, let others instead rely on Wait()

* shuffle things around to move delivery stuff into transport/ subpkg

* remove dead code

* formatting

* validate request before queueing for delivery

* finish adding code comments, fix up backoff code

* finish adding more code comments

* clamp minimum no. senders to 1

* add start/stop logging to delivery worker, some slight changes

* remove double logging

* use worker ptrs

* expose the embedded log fields in httpclient.Request{}

* ensure request context values are preserved when updating ctx

* add delivery worker tests

* fix linter issues

* ensure delivery worker gets inited in testrig

* fix tests to delivering messages to check worker delivery queue

* update error type to use ptr instead of value receiver

* fix test calling Workers{}.Start() instead of testrig.StartWorkers()

* update docs for advanced-sender-multiplier

* update to the latest activity library version

* add comment about not using httptest.Server{}

1 files changed, 4 insertions, 9 deletions

diff --git a/docs/configuration/advanced.md b/docs/configuration/advanced.md
index f776dac54..b97d8a6ba 100644
--- a/docs/configuration/advanced.md
+++ b/docs/configuration/advanced.md
@@ -119,15 +119,10 @@ advanced-throttling-multiplier: 8
 # Default: "30s"
 advanced-throttling-retry-after: "30s"
 
-# Int. CPU multiplier for the amount of goroutines to spawn in order to send messages via ActivityPub.
-# Messages will be batched so that at most multiplier * CPU count messages will be sent out at once.
-# This can be tuned to limit concurrent POSTing to remote inboxes, preventing your instance CPU
-# usage from skyrocketing when an account with many followers posts a new status.
-#
-# Messages are split among available senders, and each sender processes its assigned messages in serial.
-# For example, say a user with 1000 followers is on an instance with 2 CPUs. With the default multiplier
-# of 2, this means 4 senders would be in process at once on this instance. When the user creates a new post,
-# each sender would end up iterating through about 250 Create messages + delivering them to remote instances.
+# Int. CPU multiplier for the fixed number of goroutines to spawn in order to send messages via ActivityPub.
+# Messages will be batched and pushed to a singular queue, from which multiplier * CPU count goroutines will
+# pull and attempt deliveries. This can be tuned to limit concurrent posting to remote inboxes, preventing
+# your instance CPU usage skyrocketing when accounts with many followers post statuses.
 #
 # If you set this to 0 or less, only 1 sender will be used regardless of CPU count. This may be
 # useful in cases where you are working with very tight network or CPU constraints.