Android HttpUrlConnection EOFException

Question

I would like to know if there are known issues on Android with HttpUrlConnection and POST requests. We are experiencing intermittent EOFExceptions when maki

Answer 1

HttpURLConnection library internally maintains a pool of Connections. So, whenever a request is send, it first checks if there is an existing connection already present in the pool, based on which it decides to create a new one.

These connections are nothing but sockets, and this library by default does not closes these sockets. It may sometimes happen that a connection (socket) which is not currently being used and is present in the pool is no longer usable as the Server may choose to terminate the connection after some time. Now, since the connection even though is closed by the server, the library does not knows about it and assumes the connection/socket to be still connected. Thus it sends the new request using this stale connection and hence we get EOFException.

The best way to handle this is to check the Response Headers after each request you send. The server always sends a "Connection: Close" before terminating a connection (HTTP 1.1). So, you can use getHeaderField() and check for "Connection" field. Another thing to note is that server ONLY sends this connection field when it is about to terminate the connection. So, you need to code around this with the possibility of getting a "null" in the normal case (when server is not closing the connection)