Are you setting Connect Timeout correctly?

Application development nowadays is becoming more and more like mashing up. Unless you provide file storage service, or data repository service, there's no way you can avoid consuming 3rd party APIs / (micro-) services. In Java battlefield, most of the time, internal or external APIs are provided via RESTful interface. If this is the case, chances are to consume a web service you'll be using one of

• org.springframework.web.client.RestTemplate
• org.apache.http.impl.client.HttpClientBuilder, or its cached version
• org.apache.http.impl.client.cache.CachingHttpClientBuilder
• org.apache.http.impl.client.DefaultHttpClient, or its fluent version
• org.apache.http.client.fluent.Request

No matter which one you end up use, it's always a good practice to set timeout for HTTP clients, and this can be done only by org.apache.http.client.config.RequestConfig. Now can you please check the value you pass into RequestConfig.Builder#setConnectTimeout()? If it's significantly larger than 5(ms, not a typo here), you're not setting it correctly.

Connect timeout is used to provide QoS of the creation of TCP connection between client and server, not the whole lifecycle of the connection, or in pooled environment, from borrow to return. If this process can't finish in few milliseconds, org.apache.http.conn.ConnectTimeoutException should be thrown to speed up the exception handling. It's not the end of the world however, if you misuse it. It's just better to fail fast in case something goes wrong for better user experience, rather than wasting the x seconds you set.

Then how about the RequestConfig.Builder#setSocketTimeout()? Well, I may have another post on it. Until then, it's more like the meaning you think setConnectionTimeout has.

Never take anything for granted.