When a user disconnects from the hub, we would spawn off a goroutine
which would make a cluster request, and then update the user status
as offline in the DB.
This was another case of unbounded concurrency where the number of
goroutines spawned was user controlled. Therefore, we would see
a clear spike in DB connections on master when a lot of users
would suddenly disconnect.
To fix this, we implement concurrency control in two areas:
1. In making the cluster request. We implement a counting semaphore
per-hub to avoid making unbounded cluster requests.
2. We use a buffered channel with a periodic flusher to process
status updates.
We also add a new store method to upsert multiple statuses
in a single query. The statusUpdateThreshold is set to 32, which means
no more than 32 rows will be upserted at one time, keeping the
SQL query load reasonable.
https://mattermost.atlassian.net/browse/MM-64298
```release-note
We improve DB connection spikes on user disconnect
by processing status updates in batches.
```
* TestPool
* Store infra
* Store tests updates
* Bump maximum concurrent postgres connections
* More infra
* channels/jobs
* channels/app
* channels/api4
* Protect i18n from concurrent access
* Replace some use of os.Setenv
* Remove debug
* Lint fixes
* Fix more linting
* Fix test
* Remove use of Setenv in drafts tests
* Fix flaky TestWebHubCloseConnOnDBFail
* Fix merge
* [MM-62408] Add CI job to generate test coverage (#30284)
* Add CI job to generate test coverage
* Remove use of Setenv in drafts tests
* Fix flaky TestWebHubCloseConnOnDBFail
* Fix more Setenv usage
* Fix more potential flakyness
* Remove parallelism from flaky test
* Remove conflicting env var
* Fix
* Disable parallelism
* Test atomic covermode
* Disable parallelism
* Enable parallelism
* Add upload coverage step
* Fix codecov.yml
* Add codecov.yml
* Remove redundant workspace field
* Add Parallel() util methods and refactor
* Fix formatting
* More formatting fixes
* Fix reporting
We switch to using iterators introduced in Go 1.23
to make iteration alloc-free and fast. And since
element removal is allowed while iterating a map,
this also means we don't need to even copy the slice
any more.
While here, we also address the comment https://github.com/mattermost/mattermost/pull/30178#discussion_r1954862151.
I have simply gone back to using []string as the map
entry rather than a type alias or a redirection with
a struct.
https://mattermost.atlassian.net/browse/MM-63130
```release-note
NONE
```
* Changed back nil to len
```release-note
NONE
```
* fixing unused assignment
```release-note
NONE
```
* add benchmark
```
goos: linux
goarch: amd64
pkg: github.com/mattermost/mattermost/server/v8/channels/app/platform
cpu: Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz
│ old.txt │ new.txt │
│ sec/op │ sec/op vs base │
HubConnIndexIterator/2_users-8 93.53n ± 1% 38.09n ± 1% -59.27% (p=0.000 n=10)
HubConnIndexIterator/3_users-8 106.30n ± 0% 38.41n ± 1% -63.86% (p=0.000 n=10)
HubConnIndexIterator/4_users-8 111.30n ± 1% 38.66n ± 1% -65.27% (p=0.000 n=10)
geomean 103.4n 38.39n -62.89%
│ old.txt │ new.txt │
│ B/op │ B/op vs base │
HubConnIndexIterator/2_users-8 16.00 ± 0% 24.00 ± 0% +50.00% (p=0.000 n=10)
HubConnIndexIterator/3_users-8 24.00 ± 0% 24.00 ± 0% ~ (p=1.000 n=10) ¹
HubConnIndexIterator/4_users-8 32.00 ± 0% 24.00 ± 0% -25.00% (p=0.000 n=10)
geomean 23.08 24.00 +4.00%
¹ all samples are equal
│ old.txt │ new.txt │
│ allocs/op │ allocs/op vs base │
HubConnIndexIterator/2_users-8 1.000 ± 0% 1.000 ± 0% ~ (p=1.000 n=10) ¹
HubConnIndexIterator/3_users-8 1.000 ± 0% 1.000 ± 0% ~ (p=1.000 n=10) ¹
HubConnIndexIterator/4_users-8 1.000 ± 0% 1.000 ± 0% ~ (p=1.000 n=10) ¹
geomean 1.000 1.000 +0.00%
¹ all samples are equal
```
```release-note
NONE
```
* ForChannel test as well
```release-note
NONE
```
* review comments
```release-note
NONE
```
* fix lint errors
```release-note
NONE
```
---------
Co-authored-by: Mattermost Build <build@mattermost.com>
When Channel iteration mode is enabled, we need to ensure that
channel scoped events do not fall through to the connIndex.All()
condition. This is possible because there are multiple hubs
in a given system. So a single event will flow through all of them
and in some hubs, a channel scoped event might not have any connections.
In that case, we need to stop processing further.
https://mattermost.atlassian.net/browse/MM-62960
```release-note
NONE
```
When we added iteration by channelID, this was a known tradeoff during that.
However, it has been observed that the regular connection removal function
creates considerable blocking of the processing loop, leading to high
CPU usage and API latencies.
To fix this, we add a reverse mapping of channelIDs to connections
and their positions in the slice. This helps us to remove the connection
from the slice without iteration.
Unfortunately, this still needs to iterate through all channelIDs
during invalidation of the channel member cache. However, the user
cache invalidation is not a regular activity. So it should be an acceptable
tradeoff to make.
https://mattermost.atlassian.net/browse/MM-62960
```release-note
A new config knob ServiceSettings.EnableWebHubChannelIteration which allows a user to control the performance of websocket broadcasting. By default, this setting is turned off. If it is turned on, it improves the websocket broadcasting performance at the expense of poor performance when users join/leave a channel. It is not recommended to turn it on unless you have atleast 200,000 concurrent users actively using MM.
```
Co-authored-by: Mattermost Build <build@mattermost.com>
Tests at very high scale indicates that the iteration
of all connections during websocket broadcast starts
to become a bottleneck.
To optimize this, we move the channelMember cache from
inside web_conn.go to the hubConnectionIndex.
This involves adding a new map keyed by the channelID
and containing all webConns where the user is a member
of that channel. Subsequently, a new method needed to
be added to invalidate the cache which previously
used to happen in web_conn.
And as a last step, we remove the cache from web_conn
to reduce SQL queries to the DB.
https://mattermost.atlassian.net/browse/MM-61130
```release-note
NONE
```
We were setting the user status to offline without
checking for connections on other nodes in a cluster.
Now we implement a request-response mechanism for the whole
cluster and we check that before setting a user to offline.
https://mattermost.atlassian.net/browse/MM-57153
```release-note
Fix a bug where the user status would incorrectly be set to offline
without checking for connections in other nodes in an HA cluster.
```
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
- Bump timeouts for some cases
- Improve sleep with require/assert.EventuallyT
for better performance and reliability.
https://mattermost.atlassian.net/browse/MM-57532
```release-note
NONE
```
PR https://github.com/mattermost/mattermost/pull/22560
introduced a regression in the case where we had
multiple connections for a single user.
Because if connIndex.Remove was called during the iteration
from connIndex.ForUser, then the slice would be modified
during iteration and if a connection got removed,
then a good connection would move from the last index
to the current index. But since we would be actively
iterating, the last index would be read as nil and we would
never be able to reach the good connection.
We fix this by returning a copy of the original slice
if there are more than one elements in the slice.
https://mattermost.atlassian.net/browse/MM-56260
```release-note
Fix a bug where if there were multiple websocket
connections from a single user, then in case one connection
got removed during a broadcast, there was a possibility
that the other good connection might not get the event.
```
* MM-54238 Initial implementation
* MM-54238 Move websocket hook into app package
* MM-54238 Add tests for mentions in posted websocket messages
* Fix styling
* Fix other styling
* Idiomatic ID naming for new code
* Fix more styles
* Separate hooks to add mentions and followers
* Improved error handling for invalid types in hooks
* Rename HasChanges to ShouldProcess
* Pass broadcast hooks through hubStart
* Add test helper for asserting json unmarshaling
* Fix missing arguments in tests
* Ensure broadcast hooks are sent across the cluster and not to users
* Ensure tests actually cover following a post
* Fix code broken by merge
* Go vet again...
* Deep copy event before processing it with hooks
* Replace RemoveBroadcastHooks with WithoutBroadcastHooks
* Address feedback
* Add helper to fix type information for hook args
* Wrap WebSocketEvent and simplify BroadcastHook
* Address feedback
* Address feedback
After reliable websockets were introduced,
we would keep pushing to a webConn even after
the client has disconnected. This would lead
to the websocket.slow/full and eventually
the disconnect messages which unnecessarily
confuse the admin.
We don't log them if the connection is inactive.
We use the active field and convert it to an atomic
to use more widely.
```release-note
NONE
```
Sometimes a broad distinction of just a channelID or a userID
is not enough to efficiently send a websocket event to users.
In several cases, depending on the user and channel, we might
need to modify the message. Therefore, we introduce the
concept of a channel hook that will get executed if the scope
is set to a channel. This hook can be populated at the app layer
to perform any application specific logic to the event.
Care must be taken to avoid race conditions as the passed event
is not deep copied. It is left to the user to treat it carefully.
For this issue, the main problem was that since we don't know
which users have permissions to which channels, we had to go through
_all_ members of a channel to figure that out. This was redundant
since a large portion of those users might not even be connected
at that time.
We solve this with the channel hook where we push this check
to be performed later while actually sending the event. This
reduces the computation to be done only for _connected_ users
rather than _all_ users of a channel.
The next iteration of this should be to use websocket subscriptions
to monitor exactly which users are on that channel to even
trim down that list. That is a larger initiative to be taken later.
Tested locally with a channel of 50 users. Here are rough results:
```
With PR:
patchPost 97ms
createPost 90ms
Master:
patchPost 306ms
createPost - 298ms
```
https://mattermost.atlassian.net/browse/MM-42810
```release-note
Improve performance while sending messages
with permalinks to channels with large number of users.
```
It was a good decision in hindsight to keep the public module as 0.x
because this would have been a breaking change again.
https://mattermost.atlassian.net/browse/MM-53032
```release-note
Changed the Go module path from github.com/mattermost/mattermost-server/server/v8 to github.com/mattermost/mattermost/server/v8.
For the public facing module, it's path is also changed from github.com/mattermost/mattermost-server/server/public to github.com/mattermost/mattermost/server/public
```
* Enable products for channels tests
* increase unit test timeout; check IsConfigReadOnly
* make app-layers
* Avoid loading boards tempaltes between tests to improve speed
* Fix delete query to be compatible with both databases
* Avoid preserving the templates for boards store tests
* Run all tests in one command
* Revert "Run all tests in one command"
This reverts commit 0330f7cd8f96b47776770e8f80ba6ba18d98b8d1.
* concurrent pkg group tests in CI
* Revert "Revert "Run all tests in one command""
This reverts commit 73892fec772575ff054a99ba9e00a7b57ca74164.
* Revert "concurrent pkg group tests in CI"
This reverts commit 550fb6cdd4a7f14d9632f2626bc66f389173b5d9.
* try testing 3 subsets of packages concurrently to improve time taken
* Revert "try testing 3 subsets of packages concurrently to improve time taken"
This reverts commit 97475f3c4eafa8bbe047097e0841220884f68cdc.
---------
Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: wiggin77 <wiggin77@warpmail.net>
