Race condition with meeting creation and poller can cause meeting to end immediately

A user reported that they created a meeting and then immediately got an error when joining the meeting. From the logs, it looks like there is a race condition between meeting creation and the poller that could cause a meeting to immediately end. In this case, the poller ran in the middle of meeting creation:

scalelite-api: receives create request
scalelite-api: creates meeting in Scalelite's database
scalelite-api: sends create request to BBB
BBB: receives create request from scalelite-api; starts creating the meeting
scalelite-poller: sends getMeetingInfo request to BBB for newly-created meeting
BBB: receives getMeetingInfo request from scalelite-poller
BBB: returns meeting doesn't exist
scalelite-poller: receives meeting doesn't exist; destroys the meeting
BBB: finishes creating the meeting; returns successful
scalelite-api: receives meeting created; returns successful
scalelite-api: receives join request for meeting
scalelite-api: meeting doesn't exist; returns error

Relevant logs:

// scalelite-api
[2020-09-08T19:03:46.377908 #6]  INFO -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Started GET "/bigbluebutton/api/create?name=Test+123&meetingID=OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg&..." for ... at 2020-09-08 19:03:46 +0000
[2020-09-08T19:03:46.379320 #6]  INFO -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Processing by BigBlueButtonApiController#create as XML
[2020-09-08T19:03:46.379440 #6]  INFO -- : [e8134140-9a35-498a-85ff-a9e24cf33506]   Parameters: {"name"=>"Test 123", "meetingID"=>"OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg", ...}
[2020-09-08T19:03:46.380605 #6] DEBUG -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Creating meeting OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg in database.
[2020-09-08T19:03:46.381189 #6] DEBUG -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Meeting find_or_create: created=true on server_id=26126ec3-25df-44b5-972a-2d5b41f1e3ce (wanted 26126ec3-25df-44b5-972a-2d5b41f1e3ce)
[2020-09-08T19:03:46.381320 #6] DEBUG -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Incrementing server 26126ec3-25df-44b5-972a-2d5b41f1e3ce load by 1
[2020-09-08T19:03:46.381686 #6] DEBUG -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Creating meeting OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg on BigBlueButton server 26126ec3-25df-44b5-972a-2d5b41f1e3ce
// poller ran here
[2020-09-08T19:03:46.481595 #6]  INFO -- : [e8134140-9a35-498a-85ff-a9e24cf33506] Completed 200 OK in 102ms (Views: 0.2ms | ActiveRecord: 0.0ms | Allocations: 1301)
[2020-09-08T19:03:46.792546 #6]  INFO -- : [0f8fa145-8737-4349-a312-030d741ed5e6] Started GET "/bigbluebutton/api/join?fullName=...&meetingID=OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg&..." for ... at 2020-09-08 19:03:46 +0000
[2020-09-08T19:03:46.794082 #6]  INFO -- : [0f8fa145-8737-4349-a312-030d741ed5e6] Processing by BigBlueButtonApiController#join as XML
[2020-09-08T19:03:46.794333 #6]  INFO -- : [0f8fa145-8737-4349-a312-030d741ed5e6]   Parameters: {"fullName"=>"...", "meetingID"=>"OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg", ...}
[2020-09-08T19:03:46.796014 #6]  INFO -- : [0f8fa145-8737-4349-a312-030d741ed5e6] The requested meeting OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg does not exist

// scalelite-poller
[2020-09-08T19:03:46.407294 #6] DEBUG -- : Polling Meeting id=OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg on Server id=26126ec3-25df-44b5-972a-2d5b41f1e3ce
[2020-09-08T19:03:46.422979 #6]  INFO -- : Meeting id=OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg on Server id=26126ec3-25df-44b5-972a-2d5b41f1e3ce has ended
[2020-09-08T19:03:46.441980 #6] DEBUG -- : Polling Server id=26126ec3-25df-44b5-972a-2d5b41f1e3ce
[2020-09-08T19:03:46.460165 #6]  INFO -- : Server id=26126ec3-25df-44b5-972a-2d5b41f1e3ce online load: 1.0

// bbb
2020-09-08T19:03:46.398Z DEBUG o.b.web.controllers. - ApiController#create
2020-09-08T19:03:46.398Z DEBUG o.b.web.controllers. - [name:[Test 123], meetingID:[OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg], ...]
2020-09-08T19:03:46.424Z DEBUG o.b.web.controllers. - ApiController#getMeetingInfo
2020-09-08T19:03:46.424Z INFO  o.b.web.controllers. - Retrieving meeting e0c21292e8ec170dce2c00f0d9658a7f4e1c1750
2020-09-08T19:03:46.424Z DEBUG o.b.web.controllers. - ApiController#invalid We could not find a meeting with that meeting ID
2020-09-08T19:03:46.440Z DEBUG o.b.web.controllers. - ApiController#uploadDocuments(e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399)
2020-09-08T19:03:46.441Z DEBUG o.b.web.controllers. - ApiController#downloadAndProcessDocument(https://.../default.pdf, e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399, )
2020-09-08T19:03:46.441Z DEBUG o.b.p.PresentationUrlDownloadService - Creating dir [/var/bigbluebutton/e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399/e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399/d2d9a672040fbde2a47a10bf6c37b6a4b5ae187f-1599591826441]
2020-09-08T19:03:46.441Z INFO  o.bigbluebutton.api.MeetingService -  --analytics-- data={"duration":0,"record":true,"logCode":"create_meeting","name":"Test 123","description":"Create meeting.","meetingId":"e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399","externalMeetingId":"OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg","isBreakout":false,"webcamsOnlyForModerator":false}
2020-09-08T19:03:46.447Z INFO  o.bigbluebutton.api.MeetingService -  --analytics-- data={"duration":0,"record":true,"logCode":"meeting_started","name":"Test 123","description":"Meeting has started.","meetingId":"e0c21292e8ec170dce2c00f0d9658a7f4e1c1750-1599591826399","externalMeetingId":"OjRGyT7u-6BQFGsqOFCVEYQv1ZUnCJPvbr1Se-zmcrg","isBreakout":false}
2020-09-08T19:03:46.460Z DEBUG o.b.web.controllers. - ApiController#getMeetings
2020-09-08T19:03:46.482Z DEBUG o.b.web.controllers. - Rendering as xml

blindsidenetworks / scalelite

Race condition with meeting creation and poller can cause meeting to end immediately #320