[SPARK-6490][Docs] Add docs for rpc configurations

Added docs for rpc configurations and also fixed two places that should have been fixed in #5595.

Author: zsxwing <zsxwing@gmail.com>

Closes #5607 from zsxwing/SPARK-6490-docs and squashes the following commits:

25a6736 [zsxwing] Increase the default timeout to 120s
6e37c30 [zsxwing] Update docs
5577540 [zsxwing] Use spark.network.timeout as the default timeout if it presents
4f07174 [zsxwing] Fix unit tests
1c2cf26 [zsxwing] Add docs for rpc configurations

core/src/main/scala/org/apache/spark/util/RpcUtils.scala

@@ -48,11 +48,13 @@ object RpcUtils {
 
   /** Returns the default Spark timeout to use for RPC ask operations. */
   def askTimeout(conf: SparkConf): FiniteDuration = {
-    conf.getTimeAsSeconds("spark.rpc.askTimeout", "30s") seconds
+    conf.getTimeAsSeconds("spark.rpc.askTimeout",
+      conf.get("spark.network.timeout", "120s")) seconds
   }
 
   /** Returns the default Spark timeout to use for RPC remote endpoint lookup. */
   def lookupTimeout(conf: SparkConf): FiniteDuration = {
-    conf.getTimeAsSeconds("spark.rpc.lookupTimeout", "30s") seconds
+    conf.getTimeAsSeconds("spark.rpc.lookupTimeout",
+      conf.get("spark.network.timeout", "120s")) seconds
   }
 }

core/src/test/scala/org/apache/spark/SparkConfSuite.scala

@@ -227,7 +227,7 @@ class SparkConfSuite extends FunSuite with LocalSparkContext with ResetSystemPro
   test("akka deprecated configs") {
     val conf = new SparkConf()
 
-    assert(!conf.contains("spark.rpc.num.retries"))
+    assert(!conf.contains("spark.rpc.numRetries"))
     assert(!conf.contains("spark.rpc.retry.wait"))
     assert(!conf.contains("spark.rpc.askTimeout"))
     assert(!conf.contains("spark.rpc.lookupTimeout"))

core/src/test/scala/org/apache/spark/rpc/RpcEnvSuite.scala

@@ -156,7 +156,7 @@ abstract class RpcEnvSuite extends FunSuite with BeforeAndAfterAll {
 
     val conf = new SparkConf()
     conf.set("spark.rpc.retry.wait", "0")
-    conf.set("spark.rpc.num.retries", "1")
+    conf.set("spark.rpc.numRetries", "1")
     val anotherEnv = createRpcEnv(conf, "remote", 13345)
     // Use anotherEnv to find out the RpcEndpointRef
     val rpcEndpointRef = anotherEnv.setupEndpointRef("local", env.address, "ask-timeout")

docs/configuration.md

@@ -963,8 +963,9 @@ Apart from these, the following properties are also available, and may be useful
   <td>
     Default timeout for all network interactions. This config will be used in place of 
     <code>spark.core.connection.ack.wait.timeout</code>, <code>spark.akka.timeout</code>,
-    <code>spark.storage.blockManagerSlaveTimeoutMs</code> or
-    <code>spark.shuffle.io.connectionTimeout</code>, if they are not configured.
+    <code>spark.storage.blockManagerSlaveTimeoutMs</code>,
+    <code>spark.shuffle.io.connectionTimeout</code>, <code>spark.rpc.askTimeout</code> or
+    <code>spark.rpc.lookupTimeout</code> if they are not configured.
   </td>
 </tr>
 <tr>
@@ -982,6 +983,35 @@ Apart from these, the following properties are also available, and may be useful
     This is only relevant for the Spark shell.
   </td>
 </tr>
+<tr>
+  <td><code>spark.rpc.numRetries</code></td>
+  <td>3</td>
+    Number of times to retry before an RPC task gives up.
+    An RPC task will run at most times of this number.
+  <td>
+  </td>
+</tr>
+<tr>
+  <td><code>spark.rpc.retry.wait</code></td>
+  <td>3s</td>
+  <td>
+    Duration for an RPC ask operation to wait before retrying.
+  </td>
+</tr>
+<tr>
+  <td><code>spark.rpc.askTimeout</code></td>
+  <td>120s</td>
+  <td>
+    Duration for an RPC ask operation to wait before timing out.
+  </td>
+</tr>
+<tr>
+  <td><code>spark.rpc.lookupTimeout</code></td>
+  <td>120s</td>
+    Duration for an RPC remote endpoint lookup operation to wait before timing out.
+  <td>
+  </td>
+</tr>
 </table>
 
 #### Scheduling