是什么可能導致java.net.SocketException：recvfrom失敗：ETIMEDOUT？

Question

我的應用程式中有這個問題。 這是罕見的，很難發現。 這是一個堆棧：

2012-11-30 08:42:22.745myapp.package.MyCommand is failed.java.net.SocketException: recvfrom failed: ETIMEDOUT (Connection timed out)
at libcore.io.IoBridge.maybeThrowAfterRecvfrom(IoBridge.java:542)
at libcore.io.IoBridge.recvfrom(IoBridge.java:506)
at java.net.PlainSocketImpl.read(PlainSocketImpl.java:488)
at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:46)
at java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:240)
at org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:103)
at org.apache.http.impl.io.AbstractSessionInputBuffer.readLine(AbstractSessionInputBuffer.java:191)
at org.apache.http.impl.conn.DefaultResponseParser.parseHead(DefaultResponseParser.java:82)
at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:174)
at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:180)
at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:235)
at org.apache.http.impl.conn.AbstractClientConnAdapter.receiveResponseHeader(AbstractClientConnAdapter.java:259)
at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:279)
at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:121)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:428)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
at android.net.http.AndroidHttpClient.execute(AndroidHttpClient.java:252)
at myapp.package.HttpCommand.executeRequest(HttpCommand.java:176)
at myapp.package.HttpCommand.execute(HttpCommand.java:83)
at myapp.package.NetworkService$1.run(NetworkService.java:60)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:442)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:856)
Caused by: libcore.io.ErrnoException: recvfrom failed: ETIMEDOUT (Connection timed out)
at libcore.io.Posix.recvfromBytes(Native Method)
at libcore.io.Posix.recvfrom(Posix.java:131)
at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:164)
at libcore.io.IoBridge.recvfrom(IoBridge.java:503)
... 26 more

在我的應用程序中，我有一個類，它對服務器執行所有命令：

private static final AndroidHttpClient client = AndroidHttpClient.newInstance(TAG);

HttpUriRequest request = getRequest(context);
        HttpResponse response = client.execute(request);
        final int statusCode = response.getStatusLine().getStatusCode();
        if (HttpStatus.SC_OK == statusCode) {
            final String json = EntityUtils.toString(response.getEntity());
            handleResult(json);
            Log.i(TAG, json);
        } else {
            handleError(SERVER_CODE);
        } 

您有什么想法導致此問題的原因嗎？

Answer 1

收到“連接超時”錯誤時，我將尋找：

• 繁重的網絡連接
• 重載的服務器
• 會話的連接超時參數不足
• 在Ice Cream Sandwich和更早版本中，檢查是否與DNS雙重緩存有關。 請參閱InetAddress中的 DNS caching和問題7904：Android不支持TTL，並且將DNS結果緩存10分鍾

問候。

Answer 2

對我來說，發生以下錯誤：

• 應該答復的一方意外關閉了連接。

我的情況是：Android通過端口8080上的普通套接字連接到微處理器。問題是uC在實際發送“ OK”答復之前會關閉連接。 在此uC（ESP8266）中，發送顯然是延遲的操作。 解決方案是注釋掉關閉連接的行（此行代碼來自以前的版本，該版本中不打算答復）。 Rgds。