* MM-19548: Add a deadlock retry function for SaveChannel
A deadlock has been seen to occur in the upsertPublicChannelT method
during bulk import.
Here is a brief excerpt:
*** (1) TRANSACTION:
TRANSACTION 3141, ACTIVE 1 sec inserting
INSERT INTO
PublicChannels(Id, DeleteAt, TeamId, DisplayName, Name, Header, Purpose)
VALUES
(?, ?, ?, ?, ?, ?, ?)
ON DUPLICATE KEY UPDATE
DeleteAt = ?,
TeamId = ?,
DisplayName = ?,
Name = ?,
Header = ?,
Purpose = ?
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 76 page no 4 n bits 104 index Name of table `mydb`.`PublicChannels` trx id 3141 lock_mode X locks gap before rec insert intention waiting
** (2) TRANSACTION:
TRANSACTION 3140, ACTIVE 1 sec inserting
mysql tables in use 1, locked 1
5 lock struct(s), heap size 1136, 3 row lock(s), undo log entries 2
MySQL thread id 50, OS thread handle 140641523848960, query id 3226 172.17.0.1 mmuser update
INSERT INTO
PublicChannels(Id, DeleteAt, TeamId, DisplayName, Name, Header, Purpose)
VALUES
(?, ?, ?, ?, ?, ?, ?)
ON DUPLICATE KEY UPDATE
DeleteAt = ?,
TeamId = ?,
DisplayName = ?,
Name = ?,
Header = ?,
Purpose = ?
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 76 page no 4 n bits 104 index Name of table `mydb`.`PublicChannels` trx id 3140 lock_mode X locks gap before rec
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 76 page no 4 n bits 104 index Name of table `mydb`.`PublicChannels` trx id 3140 lock_mode X locks gap before rec insert intention waiting
*** WE ROLL BACK TRANSACTION (1)
Following is my analysis:
From the deadlock output, it can be seen that it's due to a gap lock.
And that's clear because the index is Name which is a multi-column index using Name and TeamId.
But interestingly, both transactions seem to be inserting the same data, which is what is puzzling me.
The multi-column index on Name and TeamId will guarantee that they are always unique. And from looking at the code,
it does not seem possible to me that it will try to insert the same data from 2 different transactions.
But even if they do, why does tx 2 try to acquire the same lock again when it already has that ?
Here is what I think the order of events happening
Tx 2 gets a gap lock.
Tx 1 tries to get the same gap lock.
Tx 2 tries to again get the same gap lock ?
The last step is what is puzzling me. Why does an UPSERT statement acquire 2 gap locks ? From my reading of https://dev.mysql.com/doc/refman/8.0/en/innodb-locks-set.html:
> INSERT ... ON DUPLICATE KEY UPDATE differs from a simple INSERT in that an exclusive lock rather than a shared lock is placed on the row to be updated when a duplicate-key error occurs. An exclusive index-record lock is taken for a duplicate primary key value. An exclusive next-key lock is taken for a duplicate unique key value.
From what I understand, the expectation is that there will be one X lock and one gap lock is taken.
But that's not what the deadlock output seems to say.
The general advice on the internet seems to be that deadlocks will happen and not all of them can be understood.
For now, we add a generic deadlock retry function at the store package which can be reused by other queries too.
P.S.: This is a verbatim copy of my investigation posted at https://dba.stackexchange.com/questions/268652/mysql-deadlock-upsert-query-acquiring-gap-lock-twice
Testing:
This is ofcourse hard to test because it is impossible to reproduce this. I have tested this by manually returning an error
and confirming that it indeed retries.
WARN[2020-06-19T11:18:24.9585676+05:30] A deadlock happened. Retrying. caller="sqlstore/channel_store.go:568" error="Error 1213: mydeadlock"
WARN[2020-06-19T11:18:24.959158+05:30] A deadlock happened. Retrying. caller="sqlstore/channel_store.go:568" error="Error 1213: mydeadlock"
WARN[2020-06-19T11:18:24.9595072+05:30] A deadlock happened. Retrying. caller="sqlstore/channel_store.go:568" error="Error 1213: mydeadlock"
WARN[2020-06-19T11:18:24.9595451+05:30] Deadlock happened 3 times. Giving up caller="sqlstore/channel_store.go:579"
ERRO[2020-06-19T11:18:24.9596426+05:30] Unable to save channel. caller="mlog/log.go:175" err_details="Error 1213: mydeadlock" err_where=CreateChannel http_code=500 ip_addr="::1" method=POST path=/api/v4/channels request_id=745bsj13b7f6mnmsbn3t97grbw user_id=xcof1ipipbrfxpfjf6x4p6kx9e
* Fix tests
* Address review comments
* Address review comments
* Add forgotten test
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
* Ensure time is different when second update operation occurs
* Change all sleeps to one ms
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
* add ServiceProviderIdentifier to config
* Update config, add unit test
* fix unit test, update i18n
* add english translation for error
Co-authored-by: mattermod <mattermod@users.noreply.github.com>
* MM-25261: Add 'include_deleted' parameter to get all channels API request.
* MM-25261: Adds test for deleted channels.
* MM-25261: Switches to single liner.
* MM-25261: Adhere to beta config setting for viewing archived channels.
* MM-25261: Test fix.
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
* MM-26203: Fix TestChannelStore//SearchAllChannels flake
Using random strings for channel names creates chances of collisions
when searching for specific strings.
We increase the search space increasing the size of the search string
to be searched. This reduces collisions and makes the tests more reliable.
For the "off-" family of tests, this probably needs more length. But
it would also need the tests to be changed slightly as the "off-" part
acts as a prefix. I accidentally stumbled upon it while running the test
50 times. Adding a "-" is probably good enough for now. We can revisit
if it fails again in CI.
* improved team_store tests too
* MM-24674 Update channel members by group to look at distinct autoTimezone and manualTimezone.
Instead of just doing a blanket distinct on the column since that returns more entries than expected
* Use JSON extract instead of parsing text
* Use single quotes in mysql query too
* Dont need to prepend users on unambiguous column
* Use json extract instead of shorthand
* Dont count timezone if timezone default length
* CI
Co-authored-by: mattermod <mattermod@users.noreply.github.com>
* MM-25710: Use an efficient cache serialization algorithm
We investigate 3 packages for selecting a suitable replacement
for gob encoding. The algorithm chosen was msgpack which gives
a decent boost over the standard gob encoding.
Any external schema dependent algorithms like protobuf, flatbuffers, avro,
capn'proto were not considered as that would entail converting the model structs
into separate schema objects and then code generating the Go structs.
It could be done theoretically at a later stage specifically for structs
which are in the hot path. This is a general solution for now.
The packages considered were:
- github.com/tinylib/msgp
- github.com/ugorji/go/codec
- github.com/vmihailenco/msgpack/v5
msgp uses code generation to generate encoding/decoding code without the reflection overhead.
Theoretically, therefore this is supposed to give the fastest performance. However, a major
flaw in that package is that it works only at a file/directory level, not at a package level.
Therefore, for structs which are spread across multiple files, it becomes near to impossible
to chase down all transitive dependencies to generate the code. Even if that's done, it fails
on some complex type like xml.Name and time.Time. (See: https://github.com/tinylib/msgp/issues/274#issuecomment-643654611)
Therefore, we are left with 2 choices. Both of them use the same underlying algorithm.
But msgpack/v5 wraps the encoders/decoders in a sync.Pool. To make a perfect apples-apples
comparison, I wrote a sync.Pool for ugorji/go/codec too and compared performance.
msgpack/v5 came out to be the fastest by a small margin.
benchstat master.txt ugorji.txt
name old time/op new time/op delta
LRU/simple=new-8 5.62µs ± 3% 3.68µs ± 2% -34.64% (p=0.000 n=10+10)
LRU/complex=new-8 38.4µs ± 2% 9.1µs ± 2% -76.38% (p=0.000 n=9+9)
LRU/User=new-8 75.8µs ± 2% 23.5µs ± 2% -69.01% (p=0.000 n=10+10)
LRU/Post=new-8 125µs ± 2% 21µs ± 3% -82.92% (p=0.000 n=9+10)
LRU/Status=new-8 27.6µs ± 1% 5.4µs ± 4% -80.34% (p=0.000 n=10+10)
name old alloc/op new alloc/op delta
LRU/simple=new-8 3.20kB ± 0% 1.60kB ± 0% -49.97% (p=0.000 n=10+10)
LRU/complex=new-8 15.7kB ± 0% 4.4kB ± 0% -71.89% (p=0.000 n=9+10)
LRU/User=new-8 33.5kB ± 0% 9.2kB ± 0% -72.48% (p=0.000 n=10+8)
LRU/Post=new-8 38.7kB ± 0% 4.8kB ± 0% -87.48% (p=0.000 n=10+10)
LRU/Status=new-8 10.6kB ± 0% 1.7kB ± 0% -83.50% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
LRU/simple=new-8 46.0 ± 0% 20.0 ± 0% -56.52% (p=0.000 n=10+10)
LRU/complex=new-8 324 ± 0% 48 ± 0% -85.19% (p=0.000 n=10+10)
LRU/User=new-8 622 ± 0% 108 ± 0% -82.64% (p=0.000 n=10+10)
LRU/Post=new-8 902 ± 0% 74 ± 0% -91.80% (p=0.000 n=10+10)
LRU/Status=new-8 242 ± 0% 22 ± 0% -90.91% (p=0.000 n=10+10)
11:31:48-~/mattermost/mattermost-server/services/cache2$benchstat master.txt vmi.txt
name old time/op new time/op delta
LRU/simple=new-8 5.62µs ± 3% 3.68µs ± 3% -34.59% (p=0.000 n=10+10)
LRU/complex=new-8 38.4µs ± 2% 8.7µs ± 3% -77.45% (p=0.000 n=9+10)
LRU/User=new-8 75.8µs ± 2% 20.9µs ± 1% -72.45% (p=0.000 n=10+10)
LRU/Post=new-8 125µs ± 2% 21µs ± 2% -83.08% (p=0.000 n=9+10)
LRU/Status=new-8 27.6µs ± 1% 5.1µs ± 3% -81.66% (p=0.000 n=10+10)
name old alloc/op new alloc/op delta
LRU/simple=new-8 3.20kB ± 0% 1.60kB ± 0% -49.89% (p=0.000 n=10+10)
LRU/complex=new-8 15.7kB ± 0% 4.6kB ± 0% -70.87% (p=0.000 n=9+8)
LRU/User=new-8 33.5kB ± 0% 10.3kB ± 0% -69.40% (p=0.000 n=10+9)
LRU/Post=new-8 38.7kB ± 0% 6.0kB ± 0% -84.62% (p=0.000 n=10+10)
LRU/Status=new-8 10.6kB ± 0% 1.9kB ± 0% -82.41% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
LRU/simple=new-8 46.0 ± 0% 20.0 ± 0% -56.52% (p=0.000 n=10+10)
LRU/complex=new-8 324 ± 0% 46 ± 0% -85.80% (p=0.000 n=10+10)
LRU/User=new-8 622 ± 0% 106 ± 0% -82.96% (p=0.000 n=10+10)
LRU/Post=new-8 902 ± 0% 89 ± 0% -90.13% (p=0.000 n=10+10)
LRU/Status=new-8 242 ± 0% 23 ± 0% -90.50% (p=0.000 n=10+10)
In general, we can see that the time to marshal/unmarshal pays off as the size of the struct
increases.
We can see that msgpack/v5 is faster for CPU but very slightly heavier on memory.
Since we are interested in fastest speed, we choose msgpack/v5.
As a future optimization, we can use a mix of msgpack and msgp for hot structs.
To do that, we would need to shuffle around some code so that for the hot struct,
all its dependencies are in the same file.
Let's use this in production for some time, watch grafana graphs for the hottest caches
and come back to optimizing this more once we have more data.
Side note: we have to do with micro-benchmarks for the time being, because all the caches
aren't migrated to cache2 interface yet. Once that's in, we can actually run some load tests
and do comparisons.
* Bring back missing import
* Fix tests
* new job type created that checks for expired mobile sessions and pushes notifications.
* only send session expired notifications if ExtendSessionLengthWithActivity is enabled.
* includes schema change: field added to Sessions table
* Improve CreatePostCheckOnlineStatus
We improve the flakyness of the test by making the websocket
status checks synchronous after making each request.
This makes the status responses more reliable because in very
busy CI environments the goroutine scheduler can indeed send
the response which is made by a later HTTP request before the first one.
* Update api4/post_test.go
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
* Implement prefix/suffix search on teams page
* Make Channel Page prefix/suffix search as well
* address PR comments
* add tests
* fix styling
* take postgres into account
* add more api tests
* update test
* add team store test
* write store test for team and channel
* fix lint
* update description
* revert go mod
Co-authored-by: mattermod <mattermod@users.noreply.github.com>
* add unix socket listener for mmctl local mode
* First working PoC
* Adds the channel list endpoint
* Add team list endpoint
* Add a LocalClient to the api test helper and start local mode
* Add helper to test with both SystemAdmin and Local clients
* Add some docs
* Adds TestForAllClients test helper
* Incorporating @ashishbhate's proposal for adding test names to the helpers
* [MM-24146] Add unix socket listener for mmctl local mode (#14296)
* add unix socket listener for mmctl local mode
* add a constant for local-mode socket path
* reflect review comments
* Fix init errors after merge
* Adds create channel tests
* Always init local mode to allow for enabling-disabling it via config
* Check the RemoteAddr of the request before marking session as local
* [MM-24604] Migrate get channel and get channel by name endpoints to local mode
* Remove local test conditional
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
* Removing some other fake apps
* More FakeApp removed
* Removing entirely FakeApp
* Fixing some tests
* Fixing get Cluster id from get plugin status
* Fixing failing tests
* Fixing tests
* Fixing test initialization for web
* Fixing InitServer for server tests
* Fixing InitServer for server tests
* Reverting go.sum and go.mod
* Removing unneded HTMLTemplates function in App layer
* Moving back some functions to its old place to easy the review
* Moving back some functions to its old place to easy the review
* Using the last struct2interface version
* Generating store layers
* Fixing merge problems
* Addressing PR comments
* Small fix
* Fixing app tests build
* Fixing tests
* fixing tests
* Fix tests
* Fixing tests
* Fixing tests
* Fixing tests
* Moving license to server struct
* Adding some fixes to the test compilation
* Fixing cluster and some jobs initialization
* Fixing some license tests compilation problems
* Fixing recursive cache invalidation
* Regenerating app layers
* Fix test compilation
Co-authored-by: mattermod <mattermod@users.noreply.github.com>
* Added 2 checks for app/file.go
- Check if channel id exist
- Check if user has permission to the upload file to the channel
Also added translations for 2 errors defined in app/file.go
* fixed 1 failing test that was linked with UploadFile
* Fixed small issue, according to the review.
* missed 1 review item. Just updated the code for it.
* fix 1 failing test, assuming that the file upload is required. ignoring nouser idea.
Added the translation for english for 2 newly defined errors.
* removed new line
* trying to fix the translation issue. Added the missing translations from master.
* as per discussion, we need to revert the check for user channel permission. So reverted it.
* Update app/file_test.go
Co-Authored-By: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>
* Update i18n/en.json
Co-Authored-By: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>
* Update file.go
Move the check to the top of the method.
* go fmt
Co-authored-by: mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
