HttpClient and ConnectionPoolTimeoutException

Monday, 15 November 2010

I've recently had a bit of trouble with my application's DefaultHttpClient instance throwing a ConnectionPoolTimeoutException quite consistently after a number of requests to the same location. (See bottom of the entry for a stacktrace).

There doesn't seem to be anything regarding this particular stacktrace in any of the Android developer forums up to now but coincidently Axis2 framework users (Also using Apache HttpClient) reported the same exception occuring after 3 requests to the same location, which is exactly what I experienced.

Here was my instance creation code for the HttpClient:

HttpParams params = new BasicHttpParams();
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);

SchemeRegistry schemeRegistry = new SchemeRegistry();
schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));

// Where ClientConfig.P_DEFAULT_CONN_TIMEOUT = 15 seconds
HttpConnectionParams.setConnectionTimeout(params, ClientConfig.P_DEFAULT_CONN_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, ClientConfig.P_DEFAULT_CONN_TIMEOUT);
ConnManagerParams.setTimeout(params, ClientConfig.P_DEFAULT_CONN_TIMEOUT);

httpClient = new DefaultHttpClient(new ThreadSafeClientConnManager(params, schemeRegistry), params);

If you're using TheradSafeClientConnManager be aware that there is a "Max connections per route" property available which is pretty well hidden, and again isn't mentioned in any of the example code I came across. Setting this to a higher value got rid of my issue.

ConnManagerParams.setMaxConnectionsPerRoute(params, new ConnPerRoute() {
    public int getMaxForRoute(HttpRoute httproute)
        return 10;

The stacktrace:
fetch() sending failed to url
org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection
    at org.apache.http.impl.conn.tsccm.ConnPoolByRoute.getEntryBlocking(
    at org.apache.http.impl.conn.tsccm.ConnPoolByRoute$1.getPoolEntry(
    at org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager$1.getConnection(
    at org.apache.http.impl.client.DefaultRequestDirector.execute(
    at org.apache.http.impl.client.AbstractHttpClient.execute(
    at org.apache.http.impl.client.AbstractHttpClient.execute(
    at org.apache.http.impl.client.AbstractHttpClient.execute(
    at android.os.AsyncTask$
    at java.util.concurrent.FutureTask$Sync.innerRun(
    at java.util.concurrent.ThreadPoolExecutor.runWorker(
    at java.util.concurrent.ThreadPoolExecutor$

Apache HttpClient is obviously used quite a lot by many apps yet it's configurable parameters haven't been explained in android examples as well as they should be I would say.

Samsung Galaxy Tab - Bit of a Gimmick

Tuesday, 2 November 2010

I don't normally purchase cutting edge technology on their day of release, but this time around the Galaxy Tab caught my attention. Over the last few days I followed internet reviews, opinions and videos of the release of this thing and after a while I convinced myself that I needed to buy one. I definitely needed a Froyo based device of some sorts as I've been using a 1.5 device for a long time as my main phone and that was the only piece of hardware I had for development. For development a decent handset is essential as of course you need to check your work on the real thing every now and again and the latest release emulators can be painfully slow especially in debug mode, so I went to the Carphone Warehouse yesterday on the day of release and purchased one for 499 GBP.

Probably the most expensive gadget I will ever buy, but the best price I could find - A 1GB data only 1-month rolling contract with TalkTalk (and a free month) that I can cancel any time - which I probably will in the next few days. This for 499GBP.

After 24 hours with this thing now I'm a bit surprised at the large number of positive reviews this device has received... Its main flaw is that it doesn't really fill in a space that needs to be filled! It's an oversize mobile phone that simply can't replace your laptop or netbook for any real purpose.

I use Gmail and Google Reader a lot for example, and I was thinking this would be a great device just to read my mail and browse my feeds. Replying to email with the on-screen keyboard is annoying and the mobile gmail client is no where near as good as what you'd receive on your laptop browser. The same with Google Reader. So many features that aren't available that you just end up using your laptop/netbook.

I also thought this thing would be great for Skype. No it's not. Again down to the actual Skype application for Android because it doesn't seem to support video calling at the moment and again there are far too many features that are missing from what you could be installing on your PC. Again, another reason to ditch the tablet and pick up your laptop instead.

Of course this thing won't replace your mobile phone either because it is far too big to carry around in your pocket. I was thinking of taking it to the gym this morning and to try a particular excercise / rep application and maybe to listen to some podcasts, but really having this thing AND my mobile is just silly. It works as a mobile of course and supports Bluetooth etc. but it's far too big to bring up to your ear as a mobile phone.

At a price of usually 530 GBP it is incredibly expensive for a bit of a gimmick really. I guarantee that more often than not it won't allow you to do what you want as well as your current laptop and mobile phone. You'll also look like a bit of an idiot if someone phones you on it.

And another little criticism before I go! I have a spot in the house from which I use my laptop quite often and I usually get 2 bars on my Windows 7 status bar icon. The Tab can't find my access point from the same spot! I didn't notice any review as yet which also commented on the quality of the wifi but in my opinion it's definitely not as good as my laptop wifi interface.

Sorry, but I'm not a convinced with this one. A bad impulse purchase!