If a trace collector is temporarily down, a background thread that tries to reach it is expected to survive flushSpans throwing ConnectionFailure:
HttpExceptionRequest Request {
host = "localhost"
port = 9411
secure = False
requestHeaders = [("content-type","application/json")]
path = "/api/v2/spans"
queryString = ""
method = "POST"
proxy = Nothing
rawBody = False
redirectCount = 10
responseTimeout = ResponseTimeoutDefault
requestVersion = HTTP/1.1
}
(ConnectionFailure Network.Socket.connect: <socket: 54>: does not exist (Connection refused))