yield to chronos in mplex loop

libp2p/muxers/mplex/coder.nim

@@ -40,7 +40,7 @@ proc readMplexVarint(conn: Connection): Future[Option[uint]] {.async, gcsafe.} =
     if res != VarintStatus.Success:
       return
   except LPStreamIncompleteError:
-    debug "unable to read varing", exc = getCurrentExceptionMsg()
+    trace "unable to read varint", exc = getCurrentExceptionMsg()
 
 proc readMsg*(conn: Connection): Future[Option[Msg]] {.async, gcsafe.} = 
   let headerVarint = await conn.readMplexVarint()

libp2p/muxers/mplex/mplex.nim

@@ -57,6 +57,10 @@ method handle*(m: Mplex) {.async, gcsafe.} =
     while not m.connection.closed:
       let msgRes = await m.connection.readMsg()
       if msgRes.isNone:
+        # TODO: this should ideally be poll(timeout = 100)
+        # but chronos poll() doesnt take a timeout, so it 
+        # might and does hang
+        await sleepAsync(100.millis) # yield to async loop
         continue
 
       let (id, msgType, data) = msgRes.get()