Fix: increase heartbeat frequency (#806)

There may be a possible race condition here since the timing of the
expiry and the interval are so close together.

pkg/abstractions/endpoint/buffer.go

@@ -518,15 +518,15 @@ func (rb *RequestBuffer) heartBeat(req *request, containerId string) {
 	ticker := time.NewTicker(endpointRequestHeartbeatInterval)
 	defer ticker.Stop()
 
-	rb.rdb.Set(rb.ctx, Keys.endpointRequestHeartbeat(rb.workspace.Name, rb.stubId, req.task.msg.TaskId, containerId), 1, endpointRequestHeartbeatInterval)
+	rb.rdb.Set(rb.ctx, Keys.endpointRequestHeartbeat(rb.workspace.Name, rb.stubId, req.task.msg.TaskId, containerId), 1, endpointRequestHeartbeatKeepAlive)
 	for {
 		select {
 		case <-ctx.Done():
 			return
 		case <-rb.ctx.Done():
 			return
 		case <-ticker.C:
-			rb.rdb.Set(rb.ctx, Keys.endpointRequestHeartbeat(rb.workspace.Name, rb.stubId, req.task.msg.TaskId, containerId), 1, endpointRequestHeartbeatInterval)
+			rb.rdb.Set(rb.ctx, Keys.endpointRequestHeartbeat(rb.workspace.Name, rb.stubId, req.task.msg.TaskId, containerId), 1, endpointRequestHeartbeatKeepAlive)
 		}
 	}
 }

pkg/abstractions/endpoint/endpoint.go

@@ -53,7 +53,8 @@ var (
 	endpointRoutePrefix                     string        = "/endpoint"
 	endpointServeContainerTimeout           time.Duration = 10 * time.Minute
 	endpointServeContainerKeepaliveInterval time.Duration = 30 * time.Second
-	endpointRequestHeartbeatInterval        time.Duration = 30 * time.Second
+	endpointRequestHeartbeatInterval        time.Duration = 5 * time.Second
+	endpointRequestHeartbeatKeepAlive       time.Duration = 30 * time.Second
 	endpointMinRequestBufferSize            int           = 10
 )