Refs #1755
I started with writing a test for wsConnection (WebsocketManager) where
I:
- create a WS connection
- do a simple echo call
- close it
No leaking goroutines, nor any leaking memory were detected.
For useful shortcuts see my blog post
https://blog.cosmos.network/debugging-the-memory-leak-in-tendermint-210186711420
Then I went to the rpc tests to see if calling Subscribe results in
memory growth. It did.
I used a slightly modified version of TestHeaderEvents function:
```
func TestHeaderEvents(t *testing.T) {
// memory heap before
f, err := os.Create("/tmp/mem1.mprof")
if err != nil {
t.Fatal(err)
}
pprof.WriteHeapProfile(f)
f.Close()
for i := 0; i < 100; i++ {
c := getHTTPClient()
err = c.Start()
require.Nil(t, err)
evtTyp := types.EventNewBlockHeader
evt, err := client.WaitForOneEvent(c, evtTyp, waitForEventTimeout)
require.Nil(t, err)
_, ok := evt.(types.EventDataNewBlockHeader)
require.True(t, ok)
c.Stop()
c = nil
}
runtime.GC()
// memory heap before
f, err = os.Create("/tmp/mem2.mprof")
if err != nil {
t.Fatal(err)
}
pprof.WriteHeapProfile(f)
f.Close()
// dump all running goroutines
time.Sleep(10 * time.Second)
pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)
}
```
```
Showing nodes accounting for 35159.16kB, 100% of 35159.16kB total
Showing top 10 nodes out of 48
flat flat% sum% cum cum%
32022.23kB 91.08% 91.08% 32022.23kB 91.08% github.com/tendermint/tendermint/libs/pubsub/query.(*QueryParser).Init
1056.33kB 3.00% 94.08% 1056.33kB 3.00% bufio.NewReaderSize
528.17kB 1.50% 95.58% 528.17kB 1.50% bufio.NewWriterSize
528.17kB 1.50% 97.09% 528.17kB 1.50% github.com/tendermint/tendermint/consensus.NewConsensusState
512.19kB 1.46% 98.54% 512.19kB 1.46% runtime.malg
512.08kB 1.46% 100% 512.08kB 1.46% syscall.ByteSliceFromString
0 0% 100% 512.08kB 1.46% github.com/tendermint/tendermint/consensus.(*ConsensusState).(github.com/tendermint/tendermint/consensus.defaultDecideProposal)-fm
0 0% 100% 512.08kB 1.46% github.com/tendermint/tendermint/consensus.(*ConsensusState).addVote
0 0% 100% 512.08kB 1.46% github.com/tendermint/tendermint/consensus.(*ConsensusState).defaultDecideProposal
0 0% 100% 512.08kB 1.46% github.com/tendermint/tendermint/consensus.(*ConsensusState).enterNewRound
```
100 subscriptions produce 32MB.
Again, no additional goroutines are running after the end of the test
(wsConnection readRoutine and writeRoutine both finishes). **It means
that some exiting goroutine or object is holding a reference to the
*Query objects, which are leaking.**
One of them is pubsub#loop. It's using state.queries to map queries to
clients and state.clients to map clients to queries.
Before this commit, we're not thoroughly cleaning state.queries, which
was the reason for memory leakage.
Refs #951
Jae: I don't know a good way to catch these errors in general, but
forcing pubsub's internal channel to have a capacity of 0 will reveal
bugs sooner, if the subscriber also has a 0 or small capacity ch to pull
from.
* updateToState exits early if the state isn't new, which happens after
* fast syncing. This results in not sending a NewRoundStep message. The mempool
* reactor depends on PeerState, which is updated by NewRoundStep
* messages. If the peer never sends a NewRoundStep, the mempool reactor
* will think they're behind, and never forward transactions. Note this
* only happens when `create_empty_blocks = false`, because otherwise
* peers will move through the consensus state and send a NewRoundStep
* for a new step soon anyways. Simple fix is just to send the
* NewRoundStep message during updateToState even if exit early
