MongoError No primary node is available

Question

We have upgraded to Play 2.7.0 recently and use play2-reactivemongo version 0.16.2 with reactivemongo 0.16.3. We use reactivemongo-shaded-native but also tried without.

We are connecting to a replica set with 3 nodes, MongoDB 3.6.10 on MongoDB Atlas.

The initial connection is fine and the service is running OK for a while.

But in the end we hit this error:

[error] 2019-02-15 09:40:30,466 r.api.Failover2 - [Supervisor-1/Connection-2] Got an error, no more attempts to do. Completing with a failure...

 reactivemongo.core.actors.Exceptions$PrimaryUnavailableException: MongoError['No primary node is available! (Supervisor-1/Connection-2)']
 Caused by: reactivemongo.core.actors.Exceptions$InternalState: null
    at reactivemongo.ConnectAll$IsMaster(400, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Unknown (20/20 available connections), latency=9223372036854775807, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=135, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=140, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615628>)
    at reactivemongo.IsMaster(400, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Unknown (20/20 available connections), latency=9223372036854775807, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=135, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615626>)
    at reactivemongo.ConnectAll$IsMaster(399, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Unknown (20/20 available connections), latency=9223372036854775807, authenticated={}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=135, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615623>)
    at reactivemongo.IsMaster(399, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Unknown (20/20 available connections), latency=9223372036854775807, authenticated={}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615622>)
    at reactivemongo.RefreshAll({{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Primary (20/20 available connections), latency=30591, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615486>)
    at reactivemongo.PrimaryUnavailable(<time:1550223615485>)
    at reactivemongo.ConnectAll({{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Primary (20/20 available connections), latency=30591, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223615475>)
    at reactivemongo.ConnectAll$IsMaster(397, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Primary (20/20 available connections), latency=30591, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=21, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223605498>)
    at reactivemongo.IsMaster(397, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Primary (20/20 available connections), latency=30591, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=15, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223605498>)
    at reactivemongo.ConnectAll$IsMaster(396, {{NodeSet Some(PlayappDevelopment-shard-0) Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: Primary (20/20 available connections), latency=30591, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-01-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=17, authenticated={Authenticated(admin,playapp_rw)}] | Node[playappdevelopment-shard-00-02-tedsb.mongodb.net:27017: Secondary (20/20 available connections), latency=15, authenticated={Authenticated(admin,playapp_rw)}] }})(<time:1550223605493>)

and this:

[error] 2019-02-15 09:40:25,157 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 80193 not found! complete message is Response(MessageHeader(16775938,220053,80193,1), Reply(8,0,0,1), ResponseInfo(b0706d7f))
[error] 2019-02-15 09:40:25,720 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 79580 not found! complete message is Response(MessageHeader(16776408,220065,79580,1), Reply(8,0,0,1), ResponseInfo(5c65523c))
[error] 2019-02-15 09:40:26,616 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 80346 not found! complete message is Response(MessageHeader(16776173,220060,80346,1), Reply(8,0,0,1), ResponseInfo(5613ea02))
[error] 2019-02-15 09:40:26,702 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 80457 not found! complete message is Response(MessageHeader(16776643,220079,80457,1), Reply(8,0,0,1), ResponseInfo(2fa23bb9))
[error] 2019-02-15 09:40:29,612 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 80174 not found! complete message is Response(MessageHeader(16776878,220102,80174,1), Reply(8,0,0,1), ResponseInfo(4faa6eec))
[error] 2019-02-15 09:40:30,257 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Oups. 80191 not found! complete message is Response(MessageHeader(16776643,220111,80191,1), Reply(8,0,0,1), ResponseInfo(1fb6b5e0))

It seems the application is not able to recover (completely) -- 1 of 20 requests is successful.

2019-02-15 09:59:45,476 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] Node[playappdevelopment-shard-00-00-tedsb.mongodb.net:27017: \
  Unknown (20/20 available connections), latency=9223372036854775807, authenticated={Authenticated(admin,playapp_rw)}] \
  hasn't answered in time to last ping! Please check its connectivity

There are a slew of "No channel for request" messages:

2019-03-05 15:02:58,433 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48879, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:58,580 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48880, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:58,678 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48881, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:58,777 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48882, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:58,874 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48883, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:58,972 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48884, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,069 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48885, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,220 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48886, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,318 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48887, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,416 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48888, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,514 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48889, 0, Query(0,assets.$cmd,0,1), Primary, None)
2019-03-05 15:02:59,611 r.c.a.MongoDBSystem - [Supervisor-1/Connection-2] No channel for request: Request(48890, 0, Query(0,assets.$cmd,0,1), Primary, None)

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This seems to be related to a high number of concurrent requests to the Play HTTP server, which probably saturates all the available channels to the primary node, causing any refresh of the master status to fail.

Apparently, we do not have this problem when connecting to a local replica set with only a single node.

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The question is, how do I fix this?

Can anyone make sense of the provided log messages?

Is my analysis correct, ie. can it happen that ReactiveMongo is not able to query the primary status because the channels are just "busy"?

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Update: we switched from ReactiveMongo (which served us quite well over the past 4 years) to the official mongo-scala-driver -- which was really painful, and still is (mainly because of the "Registry"-no-compile-time-type-safety concept passing Class[T]s around, and so on) but we no longer see the connection problems.

Answer 1

It seems you reached the limit of connections available: have you tried tuning the connection parameters http://reactivemongo.org/releases/0.11/documentation/tutorial/connect-database.html? Atlas usually supports more than 20 connections https://docs.atlas.mongodb.com/connection-limits/

I solved a similar issue with mongo native scala driver setting a pool of 50 connections, a longer wait queue and longer wait time (due latency in connection with Atlas)

Answer 2

It works for us after upgrading Reactive Mongo to 0.17.1