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.
Zach Ramsay
Ethan Buchman
Liamsi
Anton Kaliaev