[MAPREDUCE-6157] Connect failed in shuffle (due to NM down) could break current retry logic to tolerant NM restart.

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Duplicate
• Target Version/s: 2.6.0
• Assignee: Junping Du
• Reporter: Junping Du
• Created: 12/Nov/14 05:24
• Updated: 12/Nov/14 14:33
• Resolved: 12/Nov/14 06:30

Description

The connection failure log during NM restart is as following:

014-11-12 03:31:20,728 WARN [fetcher#23] org.apache.hadoop.mapreduce.task.reduce.Fetcher: Failed to connect to ip-172-31-37-212.ec2.internal:13562 with 4 map outputs
java.net.ConnectException: Connection refused
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:579)
        at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
        at sun.net.www.http.HttpClient.<init>(HttpClient.java:211)
        at sun.net.www.http.HttpClient.New(HttpClient.java:308)
        at sun.net.www.http.HttpClient.New(HttpClient.java:326)
        at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:996)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:932)
        at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:850)
        at org.apache.hadoop.mapreduce.task.reduce.Fetcher.connect(Fetcher.java:685)
        at org.apache.hadoop.mapreduce.task.reduce.Fetcher.setupConnectionsWithRetry(Fetcher.java:386)
        at org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyFromHost(Fetcher.java:292)
        at org.apache.hadoop.mapreduce.task.reduce.Fetcher.run(Fetcher.java:193)
2014-11-12 03:31:20,743 INFO [fetcher#22] org.apache.hadoop.mapreduce.task.reduce.Fetcher: for url=13562/mapOutput?job=job_1415762969065_0001&reduce=3&map=attempt_1415762969065_0001_m_000021_0,attempt_1415762969065_0001_m_000004_0,attempt_1415762969065_0001_m_000018_0,attempt_1415762969065_0001_m_000015_0,attempt_1415762969065_0001_m_000001_0,attempt_1415762969065_0001_m_000009_0,attempt_1415762969065_0001_m_000012_0,attempt_1415762969065_0001_m_000006_0 sent hash and received reply

We have some code to handle the retry logic for connection with a timeout (as below). But if connection get refused quickly, we only try very limited times and it get failed also quickly.

while (true) {
      try {
        connection.connect();
        break;
      } catch (IOException ioe) {
        // update the total remaining connect-timeout
        connectionTimeout -= unit;

        // throw an exception if we have waited for timeout amount of time
        // note that the updated value if timeout is used here
        if (connectionTimeout == 0) {
          throw ioe;
        }

        // reset the connect timeout for the last try
        if (connectionTimeout < unit) {
          unit = connectionTimeout;
          // reset the connect time out for the final connect
          connection.setConnectTimeout(unit);
        }
      }

We should fix this to make retry can continue until timeout.

Issue Links

• duplicates: MAPREDUCE-6156 Fetcher - connect() doesn't handle connection refused correctly