Strange SocketExceptions: connection reset and Connection timed out

Question

I have a Java TCP server and an Android TCP client. The server waits for requests and then sends 50MB of data to the Android client (who reads by looping an array and overwriting the data, so the data is not saved on the phone.) Everything works fine and dandy but at random times the client crashes with this:

java.net.SocketException: Connection timed out

and the server gets this:

java.net.SocketException: connection reset

The client reads in a loop until it has received all the data (the maximum I allow it to read in one call is 1.5MB.

The server sends like this:

connectionSocket.getOutputStream().write(new byte[1024*1024*10*5]);

I am looping the client and trying to do this transfer 5-10 times so I can take battery life measurements but I rarely get 3 successful completions of the 50MB transfer. I am really at a loss... the setup I have is really quite simple. I am willing to post code if it will help.

Here is what adb logcat says for android at the crash:

...transfering
D/WifiService(  109): got ACTION_DEVICE_IDLE
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
V/WifiMonitor(  109): Event [CTRL-EVENT-STATE-CHANGE id=1 state=8]
V/WifiStateTracker(  109): Changing supplicant state: COMPLETED ==> DORMANT
D/WifiStateTracker(  109): Reset connections and stopping DHCP
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
E/wpa_supplicant(  209): Set_key: Wrong Key
V/WifiMonitor(  109): Event [CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys]
V/WifiMonitor(  109): Event [CTRL-EVENT-STATE-CHANGE id=-1 state=8]
D/WifiStateTracker(  109): Disabling interface
D/NetworkStateTracker(  109): setDetailed state, old =CONNECTED and new state=IDLE
V/WifiMonitor(  109): Event [CTRL-EVENT-DRIVER-STATE STOPPED]
V/WifiStateTracker(  109): New network state is DISCONNECTED
V/WifiStateTracker(  109): Changing supplicant state: DORMANT ==> DORMANT
D/ConnectivityService(  109): ConnectivityChange for WIFI: DISCONNECTED/IDLE
D/ConnectivityService(  109): getMobileDataEnabled returning false
D/ConnectivityService(  109): not failing over to mobile type 0 because Mobile Data Disabled
D/ConnectivityService(  109): not failing over to mobile type 2 because Mobile Data Disabled
D/ConnectivityService(  109): not failing over to mobile type 3 because Mobile Data Disabled
D/ConnectivityService(  109): not failing over to mobile type 4 because Mobile Data Disabled
D/ConnectivityService(  109): not failing over to mobile type 5 because Mobile Data Disabled
D/Tethering(  109): Tethering got CONNECTIVITY_ACTION
D/Tethering(  109): MasterInitialState.processMessage what=3
E/HierarchicalStateMachine(  109): TetherMaster - unhandledMessage: msg.what=3
I/ActivityManager(  109): Start proc android.process.media for broadcast com.android.providers.downloads/.DownloadReceiver: pid=793 uid=10004 gids={1015, 2001, 3003}
D/NetworkLocationProvider(  109): updateNetworkState(): Updating network state to 1
I/ActivityThread(  793): Publishing provider media: com.android.providers.media.MediaProvider
V/MediaProvider(  793): Attached volume: internal
V/MediaProvider(  793): /mnt/sdcard volume ID: 845505849
V/MediaProvider(  793): Attached volume: external
I/ActivityThread(  793): Publishing provider downloads: com.android.providers.downloads.DownloadProvider
I/ActivityThread(  793): Publishing provider drm: com.android.providers.drm.DrmProvider
I/GTalkService(  243): [ServiceAutoStarter] --- connectivity changed
I/GTalkService(  243): [ServiceAutoStarter] --- start GTalk service ---
I/ActivityManager(  109): Start proc com.google.android.apps.uploader for broadcast com.google.android.apps.uploader/.ConnectivityBroadcastReceiver: pid=801 uid=10027 gids={3003}
D/GTalkService(  243): [GTalkService.1] onStartCommand: found 0 connections, force audit connections...
D/GoogleLoginService(  243): onBind: Intent { act=android.accounts.AccountAuthenticator cmp=com.google.android.gsf/.loginservice.GoogleLoginService }
W/GoogleLoginService(  243): Device has no accounts: sending Intent { act=com.google.android.gsf.LOGIN_ACCOUNTS_MISSING }
D/GTalkService(  243): [GTalkService.25] account missing
I/ActivityThread(  801): Publishing provider com.google.android.apps.uploader: com.google.android.apps.uploader.UploadsContentProvider
I/ActivityThread(  801): Publishing provider com.google.photos.provider.Album: com.google.android.apps.uploader.clients.picasa.AlbumProvider
D/MediaUploader(  801): UploaderApplication.onCreate
D/MediaUploader(  801): nonWifiLimit=20971520, default=20971520
I/MediaUploader(  801): No need to wake up
I/ActivityManager(  109): Process com.google.android.apps.genie.geniewidget (pid 442) has died.
W/ActivityManager(  109): Scheduling restart of crashed service com.google.android.apps.genie.geniewidget/.GenieRefreshService in 5000ms
I/IO exception (  766): ******************** Log Msg IOE java.net.SocketException: Connection timed out
**W/System.err(  766): java.net.SocketException: Connection timed out
W/System.err(  766):    at org.apache.harmony.luni.platform.OSNetworkSystem.readSocketImpl(Native Method)
W/System.err(  766):    at org.apache.harmony.luni.platform.OSNetworkSystem.read(OSNetworkSystem.java:358)
W/System.err(  766):    at org.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:561)
W/System.err(  766):    at org.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:88)
W/System.err(  766):    at com.mdog.datareceive.Receive$1.onReceive(Receive.java:71)
W/System.err(  766):    at android.app.ActivityThread$PackageInfo$ReceiverDispatcher$Args.run(ActivityThread.java:892)
W/System.err(  766):    at android.os.Handler.handleCallback(Handler.java:587)
W/System.err(  766):    at android.os.Handler.dispatchMessage(Handler.java:92)
W/System.err(  766):    at android.os.Looper.loop(Looper.java:123)
W/System.err(  766):    at android.app.ActivityThread.main(ActivityThread.java:4627)
W/System.err(  766):    at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err(  766):    at java.lang.reflect.Method.invoke(Method.java:521)
W/System.err(  766):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
W/System.err(  766):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
W/System.err(  766):    at dalvik.system.NativeStart.main(Native Method)**
I/ActivityManager(  109): Start proc com.google.android.apps.genie.geniewidget for service com.google.android.apps.genie.geniewidget/.GenieRefreshService: pid=811 uid=10031 gids={3003, 1015}

Here is the server exception:

Exception in thread "main" java.net.SocketException: Connection reset
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:96)
    at java.net.SocketOutputStream.write(SocketOutputStream.java:124)
    at com.mdog.tcpserver.ServerDriver.main(ServerDriver.java:55)

Answer 1

Increase connect timeout to solve my problem. The default value is 10 seconds.

OkHttpClient.Builder builder = new OkHttpClient.Builder();

builder.connectTimeout(15, TimeUnit.SECONDS);

Answer 2

I was experiencing the same problem, as I do a heavy data download that takes over 10 minutes. When the device went to sleep I got the java.net.SocketException: Connection timed out.

I tried the solution stated by @Michael, using a WakeLock during the download. That not fixed the full problem for me, because if the user pressed the power button I was experiencing the same issue. If it was not pressed that worked because you were preventing Android to sleep with the WakeLock and Wifi was not turned off...

Finally, I came across that the problem was not the CPU sleeping it was that wifi is switched off when the screen turns off. So I used a WifiLock and that fixed the problem!

My code to work with WakeLocks look like (of course, I do the actual work in an AsyncTask -take it as pseudocode-):

WifiManager wifiManager = (WifiManager)getSystemService(WIFI_SERVICE);
WifiLock wifiLock = wifiManager.createWifiLock("long_download");
wifiLock.acquire();
// Do the heavy work in background
wifiLock.release();

You will need the following permission in your AndroidManifest:

<uses-permission android:name="android.permission.WAKE_LOCK"/>

Answer 3

There are various reasons why the connection drops, ranging from the infrastructure (as Dan pointed out) to the device going to sleep. You might want to try requesting a wakelock and see if this helps. Also, by randomly pressing the touch screen to keep the device from sleeping could see if this is sleep-related.

On the other hand, if you just catch the Exception and immediately reconnect and retry, your measurements shouldn't be off by too much. You might also want to try UDP instead of TCP (no timeouts possible). Be sure to monitor if the throughput drops though.

Answer 4

Just guessing, but I don't think it's your code; I think it's a network issue. I've known some WiFi routers (*cough* Linksys *cough*) that had trouble handling that much data at one time. Try disabling WiFi and testing with 3G. Or, since your purpose is to test battery life and not throughput, try breaking up the data writes into smaller chunks, with a brief pause between each chunk (say, 100K chunks, with delays of somewhere around 10 to 100 ms.) This may skew your test results a bit, but you can account for that easily enough by factoring in the battery consumption during the total duration of those (presumably idle) pauses.