差異處
這裏顯示兩個版本的差異處。
| 下次修改 | 前次修改 | ||
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java:basic:httpurlconnection:readblockingissue [2018/03/21 21:09] tony 建立 |
java:basic:httpurlconnection:readblockingissue [2023/06/25 09:48] (目前版本) |
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| 行 2: | 行 2: | ||
| ====== Read Blocking of the HttpsURLConnection ====== | ====== Read Blocking of the HttpsURLConnection ====== | ||
| ===== Problem ===== | ===== Problem ===== | ||
| + | 這故事發生在某天service狀態顯示為啟動中，但卻沒執行該執行的工作。後來將heap dump出來，從thread list中看到以下狀況:\\ | ||
| + | {{:java:basic:httpurlconnection:read_blocking_of_httpsurlconnection.png|}}\\ | ||
| + | 我們的URLConnection是有設定timeout的: | ||
| + | <code java> | ||
| + | URLConnection conn = url.openConnection(); | ||
| + | conn.setConnectTimeout(connectionTimeout); | ||
| + | conn.setReadTimeout(readTimeout); | ||
| + | </code> | ||
| + | 為什麼service已經執行好幾天了，還會存在理應timeout的連線呢? | ||
| ===== How to resolve? ===== | ===== How to resolve? ===== | ||
| + | 從call stack中去查看java原始碼可以發現，在sun.net.www.protocol.https.HttpsClient.afterConnect中，會使用SSLSocketFactory去建立socket並且做handshake，期間並沒有設定readTimeout；如果http server並沒吐訊息或自動中斷連線，就有可能造成client程式block住。在這種情況下，即使你做中斷也沒用。\\ | ||
| + | 目前我們解決的方式是透過一個wrapper SSLSocketFactory，去設定default timeout: | ||
| + | <code java> | ||
| + | private Socket setDefaultProp(Socket socket) throws SocketException{ | ||
| + | socket.setSoTimeout(readTimeout); | ||
| + | return socket; | ||
| + | } | ||
| + | |||
| + | @Override | ||
| + | public Socket createSocket(Socket aS, String aHost, int aPort, boolean aAutoClose) throws IOException { | ||
| + | return setDefaultProp(mSocketFactory.createSocket(aS, aHost, aPort, aAutoClose)); | ||
| + | } | ||
| + | </code> | ||
| + | 而HttpsURLConnection會設定我們自己的SSLSocketFactory: | ||
| + | <code java> | ||
| + | HttpsURLConnection sslconn = (HttpsURLConnection) conn; | ||
| + | sslconn.setSSLSocketFactory(mySSLSocketFactory); | ||
| + | </code> | ||
| ===== ===== | ===== ===== | ||
| ---- | ---- | ||
| \\ | \\ | ||
| ~~DISQUS~~ | ~~DISQUS~~ | ||
