HADOOP-16656. Document FairCallQueue configs in core-default.xml. Contributed by Siyao Meng.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -2274,6 +2274,193 @@
     because the server side is stuck in TIME_WAIT state.
   </description>
 </property>
+
+<!-- FairCallQueue properties -->
+<!-- See FairCallQueue documentation for a table of all properties -->
+
+<!-- [port_number] is the port used by the IPC server to be configured. -->
+<!-- For example, ipc.8020.callqueue.impl will adjust the call queue    -->
+<!-- implementation for the IPC server running at port 8020.            -->
+
+<!-- Typically, [port_number] is configured to be the NameNode RPC port,    -->
+<!-- i.e. port number in dfs.namenode.rpc-address, or port number in        -->
+<!-- fs.defaultFS if dfs.namenode.rpc-address is not explicitly configured. -->
+<property>
+  <name>ipc.[port_number].backoff.enable</name>
+  <value>false</value>
+  <description>Whether or not to enable client backoff when a queue is full.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].callqueue.impl</name>
+  <value>java.util.concurrent.LinkedBlockingQueue</value>
+  <description>The fully qualified name of a class to use as the implementation
+    of a call queue. The default implementation is
+    java.util.concurrent.LinkedBlockingQueue (FIFO queue).
+    Use org.apache.hadoop.ipc.FairCallQueue for the Fair Call Queue.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].scheduler.impl</name>
+  <value>org.apache.hadoop.ipc.DefaultRpcScheduler</value>
+  <description>The fully qualified name of a class to use as the
+    implementation of the scheduler. The default implementation is
+    org.apache.hadoop.ipc.DefaultRpcScheduler (no-op scheduler) when not using
+    FairCallQueue. If using FairCallQueue, defaults to
+    org.apache.hadoop.ipc.DecayRpcScheduler. Use
+    org.apache.hadoop.ipc.DecayRpcScheduler in conjunction with the Fair Call
+    Queue.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].scheduler.priority.levels</name>
+  <value>4</value>
+  <description>How many priority levels to use within the scheduler and call
+    queue. This property applies to RpcScheduler and CallQueue.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].faircallqueue.multiplexer.weights</name>
+  <value>8,4,2,1</value>
+  <description>How much weight to give to each priority queue. This should be
+    a comma-separated list of length equal to the number of priority levels.
+    Weights descend by a factor of 2 (e.g., for 4 levels: 8,4,2,1).
+    This property applies to WeightedRoundRobinMultiplexer.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].identity-provider.impl</name>
+  <value>org.apache.hadoop.ipc.UserIdentityProvider</value>
+  <description>The identity provider mapping user requests to their identity.
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].cost-provider.impl</name>
+  <value>org.apache.hadoop.ipc.DefaultCostProvider</value>
+  <description>The cost provider mapping user requests to their cost. To
+    enable determination of cost based on processing time, use
+    org.apache.hadoop.ipc.WeightedTimeCostProvider.
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.period-ms</name>
+  <value>5000</value>
+  <description>How frequently the decay factor should be applied to the
+    operation counts of users. Higher values have less overhead, but respond
+    less quickly to changes in client behavior.
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.decay-factor</name>
+  <value>0.5</value>
+  <description>When decaying the operation counts of users, the multiplicative
+    decay factor to apply. Higher values will weight older operations more
+    strongly, essentially giving the scheduler a longer memory, and penalizing
+    heavy clients for a longer period of time.
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.thresholds</name>
+  <value>13,25,50</value>
+  <description>The client load threshold, as an integer percentage, for each
+    priority queue. Clients producing less load, as a percent of total
+    operations, than specified at position i will be given priority i. This
+    should be a comma-separated list of length equal to the number of priority
+    levels minus 1 (the last is implicitly 100).
+    Thresholds ascend by a factor of 2 (e.g., for 4 levels: 13,25,50).
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.backoff.responsetime.enable</name>
+  <value>false</value>
+  <description>Whether or not to enable the backoff by response time feature.
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.backoff.responsetime.thresholds</name>
+  <value>10s,20s,30s,40s</value>
+  <description>The response time thresholds, as time durations, for each
+    priority queue. If the average response time for a queue is above this
+    threshold, backoff will occur in lower priority queues. This should be a
+    comma-separated list of length equal to the number of priority levels.
+    Threshold increases by 10s per level (e.g., for 4 levels: 10s,20s,30s,40s)
+    This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].decay-scheduler.metrics.top.user.count</name>
+  <value>10</value>
+  <description>The number of top (i.e., heaviest) users to emit metric
+    information about. This property applies to DecayRpcScheduler.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].weighted-cost.lockshared</name>
+  <value>10</value>
+  <description>The weight multiplier to apply to the time spent in the
+    processing phase which holds a shared (read) lock.
+    This property applies to WeightedTimeCostProvider.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].weighted-cost.lockexclusive</name>
+  <value>100</value>
+  <description>The weight multiplier to apply to the time spent in the
+    processing phase which holds an exclusive (write) lock.
+    This property applies to WeightedTimeCostProvider.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].weighted-cost.handler</name>
+  <value>1</value>
+  <description>The weight multiplier to apply to the time spent in the
+    HANDLER phase which do not involve holding a lock.
+    See org.apache.hadoop.ipc.ProcessingDetails.Timing for more details on
+    this phase. This property applies to WeightedTimeCostProvider.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].weighted-cost.lockfree</name>
+  <value>1</value>
+  <description>The weight multiplier to apply to the time spent in the
+    LOCKFREE phase which do not involve holding a lock.
+    See org.apache.hadoop.ipc.ProcessingDetails.Timing for more details on
+    this phase. This property applies to WeightedTimeCostProvider.
+  </description>
+</property>
+
+<property>
+  <name>ipc.[port_number].weighted-cost.response</name>
+  <value>1</value>
+  <description>The weight multiplier to apply to the time spent in the
+    RESPONSE phase which do not involve holding a lock.
+    See org.apache.hadoop.ipc.ProcessingDetails.Timing for more details on
+    this phase. This property applies to WeightedTimeCostProvider.
+  </description>
+</property>
+
 <!-- Proxy Configuration -->
 
 <property>