fix: make websockets non-blocking

.changeset/websockets-non-blocking.md

@@ -0,0 +1,19 @@
+---
+"@empirica/core": patch
+---
+
+Make the websocket connection non-blocking. This fixes issues where a zombie
+websocket connection (not disconnected, but not keeping up with the messages
+sent) could lock up the server. What we call zombie connections can happen when
+a client is either totally non-responsive, or when the client is too slow to
+process messages. Now, we will queue up to 500 messages per GraphQL
+subscription, and if the client does not keep up, we will drop the connection.
+
+This also makes websocket sends non-blocking, so we are no longer sending as
+slowly as the slowest connection. This should greatly improve performance for
+most clients that have a good connection. For clients with a bad connection,
+they will still be slow, there is not much we can do about their internet
+connection. But they will not slow down the server for everyone else. And we
+have clear limits on how many messages we will queue up for them, so their
+connection will reset after a while, which could help them reconnect and get a
+better connection.

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/charmbracelet/lipgloss v0.5.0
 	github.com/cortesi/moddwatch v0.0.0-20210323234936-df014e95c743
 	github.com/davecgh/go-spew v1.1.1
-	github.com/empiricaly/tajriba v1.4.0
+	github.com/empiricaly/tajriba v1.4.1
 	github.com/go-playground/validator/v10 v10.11.0
 	github.com/jpillora/backoff v1.0.0
 	github.com/json-iterator/go v1.1.12

go.sum

@@ -91,8 +91,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgryski/trifles v0.0.0-20200323201526-dd97f9abfb48 h1:fRzb/w+pyskVMQ+UbP35JkH8yB7MYb4q/qhBarqZE6g=
 github.com/dgryski/trifles v0.0.0-20200323201526-dd97f9abfb48/go.mod h1:if7Fbed8SFyPtHLHbg49SI7NAdJiC5WIA09pe59rfAA=
-github.com/empiricaly/tajriba v1.4.0 h1:BPXa3JcuaLGebZ18dDOxXf6PpWbJanzrJylebpxErUQ=
-github.com/empiricaly/tajriba v1.4.0/go.mod h1:TqAM0iRbN78gE5vnZ1Ot6PQOidfYM5FwIdoU/UB+wrE=
+github.com/empiricaly/tajriba v1.4.1 h1:ki2Y+3ljg832n37X37Lj/VLuFSoLZc6GF7cmTviMkY4=
+github.com/empiricaly/tajriba v1.4.1/go.mod h1:TqAM0iRbN78gE5vnZ1Ot6PQOidfYM5FwIdoU/UB+wrE=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=