Android Error: java.net.SocketException: Socket closed

Question

I'm seeing this error come up in my crash logs hundreds of times a week but I have spent at this point several weeks trying to chase down the error without any success. I have been unable to reproduce it on any of my devices. Here's the stack trace:

Posix.java:-2 in "libcore.io.Posix.recvfromBytes"
Posix.java:131 in "libcore.io.Posix.recvfrom"
BlockGuardOs.java:164 in "libcore.io.BlockGuardOs.recvfrom"
IoBridge.java:513 in "libcore.io.IoBridge.recvfrom"
PlainSocketImpl.java:489 in "java.net.PlainSocketImpl.read"
PlainSocketImpl.java:46 in "java.net.PlainSocketImpl.access$000"
PlainSocketImpl.java:241 in "java.net.PlainSocketImpl$PlainSocketInputStream.read"
AbstractSessionInputBuffer.java:103 in "org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer"
AbstractSessionInputBuffer.java:191 in "org.apache.http.impl.io.AbstractSessionInputBuffer.readLine"
DefaultResponseParser.java:82 in "org.apache.http.impl.conn.DefaultResponseParser.parseHead"
AbstractMessageParser.java:174 in "org.apache.http.impl.io.AbstractMessageParser.parse"
AbstractHttpClientConnection.java:180 in "org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader"
DefaultClientConnection.java:235 in "org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader"
AbstractClientConnAdapter.java:259 in "org.apache.http.impl.conn.AbstractClientConnAdapter.receiveResponseHeader"
HttpRequestExecutor.java:279 in "org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse"
HttpRequestExecutor.java:121 in "org.apache.http.protocol.HttpRequestExecutor.execute"
DefaultRequestDirector.java:428 in "org.apache.http.impl.client.DefaultRequestDirector.execute"
AbstractHttpClient.java:555 in "org.apache.http.impl.client.AbstractHttpClient.execute"
AbstractHttpClient.java:487 in "org.apache.http.impl.client.AbstractHttpClient.execute"
AbstractHttpClient.java:465 in "org.apache.http.impl.client.AbstractHttpClient.execute"
Utilities.java:484 in "com.myapp.android.Utilities$8.run"

Here's the block of code where the error is coming from... the exact where the crash occurs is HttpResponse response = httpclient.execute(httppost);:

 public static HttpPost postData(String URL, final List<NameValuePair> params, final Handler handler) {
        // Create a new HttpClient and Post Header
        //android.util.Log.d("Utilities", "Called postData");
        final HttpClient httpclient = new DefaultHttpClient();
        //httpclient.
        final HttpPost httppost = new HttpPost(URL);
        final Message msg = new Message();
        final Bundle dataBundle = new Bundle();
        final ByteArrayOutputStream out = new ByteArrayOutputStream();

        new Thread(){
            @Override
            public void run(){
                String error = "";
                String data = "";
                try {
                    httppost.setEntity(new UrlEncodedFormEntity(params));
                    HttpResponse response = httpclient.execute(httppost);
                    StatusLine statusLine = response.getStatusLine();
                    if(statusLine.getStatusCode() == HttpStatus.SC_OK){
                        response.getEntity().writeTo(out);
                        out.close();
                        data = out.toString();
                    } else{
                        error = EntityUtils.toString(response.getEntity());
                    }
                } catch (ClientProtocolException e) {
                    AirbrakeNotifier.notify(e);
                    error = e.toString();
                } catch (IOException e) {
                    AirbrakeNotifier.notify(e);
                    error = e.toString();
                } catch (Exception ex) {
                    AirbrakeNotifier.notify(ex);
                    error = ex.toString();
                }
                dataBundle.putString("error", error);
                dataBundle.putString("data", data);
                msg.setData(dataBundle);
                handler.dispatchMessage(msg);
            }
        }.start();
        return httppost;
    }

Any help on finally figuring this one out is greatly appreciated!

Answer 1

In my opinion, the culprit of this problem is not your app, but the remote side (i.e., the HTTP server). The most probable thing is that the HTTP server is suddenly resetting the connection and this causes a SocketException in your app. In production environments, these things happen quite often. It might be caused by an overload of the HTTP server, some exceptional circumstance that might make the server close (HTTP request flood, or even an incremented number of requests when the remote server has run out of resources; the server could also run out of its local socket pool... reasons might be dozens).

If the proportion of these errors is low in comparison with the successful HTTP requests, I wouldn't worry much, I'd just wrap that piece of code into a try { ... } catch (SocketException e) { ... } statement and show to the user a dialog telling them that the request has failed and they should retry.

What I would certainly do is try to determine the reason of this behavior: I'd try to match the time of one of these exceptions and try to dig into the HTTP server logs nearly to that time to try to determine the cause of this sudden disconnection (assuming you have access to that logs and other diagnostic tools). As I said before, it might be a silly thing or a bit more complex to debug, but I'd bet this is the problem.