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Add weighted request scheduler. patch by Jeremy Hanna; reviewed by Stu Hood for CASSANDRA-1485 

git-svn-id: https://svn.apache.org/repos/asf/cassandra/trunk@1000640 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jonathan Ellis 2010-09-23 21:42:01 +00:00
parent 665965a2a2
commit 93d3a22e10
7 changed files with 83 additions and 33 deletions
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1
CHANGES.txt
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@ -86,6 +86,7 @@
* remove Clock from the Thrift (and Avro) API (CASSANDRA-1501)
* Close intra-node sockets when connection is broken (CASSANDRA-1528)
* RPM packaging spec file (CASSANDRA-786)
* weighted request scheduler (CASSANDRA-1485)
0.7-beta1

21
conf/cassandra.yaml
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@ -210,9 +210,9 @@ dynamic_snitch: true
# not affect inter node communication.
# org.apache.cassandra.scheduler.NoScheduler - No scheduling takes place
# org.apache.cassandra.scheduler.RoundRobinScheduler - Round robin of
# client requests to a node with a sepearte queue for each
# reques_scheduler_id. The requests are throttled based on the limit set
# in throttle_limit in the requeset_scheduler_options
# client requests to a node with a separate queue for each
# request_scheduler_id. The scheduler is further customized by
# request_scheduler_options as described below.
request_scheduler: org.apache.cassandra.scheduler.NoScheduler
# Scheduler Options vary based on the type of scheduler
@ -224,12 +224,23 @@ request_scheduler: org.apache.cassandra.scheduler.NoScheduler
# running requests can complete.
# The value of 80 here is twice the number of
# concurrent_reads + concurrent_writes.
# - default_weight -- default_weight is optional and allows for
# overriding the default which is 1.
# - weights -- Weights are optional and will default to 1 or the
# overridden default_weight. The weight translates into how
# many requests are handled during each turn of the
# RoundRobin, based on the scheduler id.
#
# request_scheduler_options:
# throttle_limit: 80
# default_weight: 5
# weights:
# Keyspace1: 1
# Keyspace2: 5
# request_scheduler_id -- An identifer based on which to perform
# the request scheduling. The current supported option is "keyspace"
request_scheduler_id: keyspace
# the request scheduling. Currently the only valid option is keyspace.
# request_scheduler_id: keyspace
# A ColumnFamily is the Cassandra concept closest to a relational table.
#

2
src/java/org/apache/cassandra/avro/CassandraServer.java
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@ -822,7 +822,7 @@ public class CassandraServer implements Cassandra {
*/
private void schedule()
{
requestScheduler.queue(Thread.currentThread(), clientState.getSchedulingId());
requestScheduler.queue(Thread.currentThread(), clientState.getSchedulingValue());
}
/**

9
src/java/org/apache/cassandra/config/RequestSchedulerOptions.java
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@ -1,4 +1,6 @@
package org.apache.cassandra.config;
import java.util.Map;
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
@ -25,5 +27,10 @@ package org.apache.cassandra.config;
*/
public class RequestSchedulerOptions
{
public Integer throttle_limit = 80;
public static final Integer DEFAULT_THROTTLE_LIMIT = 80;
public static final Integer DEFAULT_WEIGHT = 1;
public Integer throttle_limit = DEFAULT_THROTTLE_LIMIT;
public Integer default_weight = DEFAULT_WEIGHT;
public Map<String, Integer> weights;
}

65
src/java/org/apache/cassandra/scheduler/RoundRobinScheduler.java
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@ -26,6 +26,7 @@ import java.util.concurrent.Semaphore;
import java.util.concurrent.SynchronousQueue;
import org.apache.cassandra.config.RequestSchedulerOptions;
import org.apache.cassandra.utils.Pair;
import org.cliffc.high_scale_lib.NonBlockingHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -33,12 +34,15 @@ import org.slf4j.LoggerFactory;
/**
* A very basic Round Robin implementation of the RequestScheduler. It handles
* request groups identified on user/keyspace by placing them in separate
* queues and servicing a request from each queue in a RoundRobin fashion.
* queues and servicing a request from each queue in a RoundRobin fashion.
* It optionally adds weights for each round.
*/
public class RoundRobinScheduler implements IRequestScheduler
{
private static final Logger logger = LoggerFactory.getLogger(RoundRobinScheduler.class);
private final NonBlockingHashMap<String, SynchronousQueue<Thread>> queues;
//The Pair is the weighted queue - the left is the weight and the right is the queue
private final NonBlockingHashMap<String, Pair<Integer, SynchronousQueue<Thread>>> queues;
private static boolean started = false;
private final Semaphore taskCount;
@ -46,12 +50,18 @@ public class RoundRobinScheduler implements IRequestScheduler
// Used by the the scheduler thread so we don't need to busy-wait until there is a request to process
private final Semaphore queueSize = new Semaphore(0, false);
private Integer defaultWeight;
private Map<String, Integer> weights;
public RoundRobinScheduler(RequestSchedulerOptions options)
{
assert !started;
defaultWeight = options.default_weight;
weights = options.weights;
taskCount = new Semaphore(options.throttle_limit);
queues = new NonBlockingHashMap<String, SynchronousQueue<Thread>>();
queues = new NonBlockingHashMap<String, Pair<Integer, SynchronousQueue<Thread>>>();
Runnable runnable = new Runnable()
{
public void run()
@ -70,12 +80,12 @@ public class RoundRobinScheduler implements IRequestScheduler
public void queue(Thread t, String id)
{
SynchronousQueue<Thread> queue = getQueue(id);
Pair<Integer, SynchronousQueue<Thread>> weightedQueue = getWeightedQueue(id);
try
{
queueSize.release();
queue.put(t);
weightedQueue.right.put(t);
}
catch (InterruptedException e)
{
@ -90,14 +100,26 @@ public class RoundRobinScheduler implements IRequestScheduler
private void schedule()
{
int weight;
SynchronousQueue<Thread> queue;
Thread t;
queueSize.acquireUninterruptibly();
for (SynchronousQueue<Thread> queue : queues.values())
for (Map.Entry<String,Pair<Integer, SynchronousQueue<Thread>>> request : queues.entrySet())
{
Thread t = queue.poll();
if (t != null)
weight = request.getValue().left;
queue = request.getValue().right;
//Using the weight, process that many requests at a time (for that scheduler id)
for (int i=0; i<weight; i++)
{
taskCount.acquireUninterruptibly();
queueSize.acquireUninterruptibly();
t = queue.poll();
if (t == null)
break;
else
{
taskCount.acquireUninterruptibly();
queueSize.acquireUninterruptibly();
}
}
}
queueSize.release();
@ -107,25 +129,32 @@ public class RoundRobinScheduler implements IRequestScheduler
* Get the Queue for the respective id, if one is not available
* create a new queue for that corresponding id and return it
*/
private SynchronousQueue<Thread> getQueue(String id)
private Pair<Integer, SynchronousQueue<Thread>> getWeightedQueue(String id)
{
SynchronousQueue<Thread> queue = queues.get(id);
if (queue != null)
Pair<Integer, SynchronousQueue<Thread>> weightedQueue = queues.get(id);
if (weightedQueue != null)
// queue existed
return queue;
return weightedQueue;
SynchronousQueue<Thread> maybenew = new SynchronousQueue<Thread>(true);
queue = queues.putIfAbsent(id, maybenew);
if (queue == null)
Pair<Integer, SynchronousQueue<Thread>> maybenew = new Pair(getWeight(id), new SynchronousQueue<Thread>(true));
weightedQueue = queues.putIfAbsent(id, maybenew);
if (weightedQueue == null)
// created new queue
return maybenew;
// another thread created the queue
return queue;
return weightedQueue;
}
Semaphore getTaskCount()
{
return taskCount;
}
private int getWeight(String weightingVar)
{
return (weights != null && weights.containsKey(weightingVar))
? weights.get(weightingVar)
: defaultWeight;
}
}

16
src/java/org/apache/cassandra/service/ClientState.java
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@ -38,9 +38,6 @@ import org.apache.cassandra.thrift.InvalidRequestException;
public class ClientState
{
private static Logger logger = LoggerFactory.getLogger(ClientState.class);
// true if the keyspace should be used as the scheduling id
private final boolean SCHEDULE_ON_KEYSPACE = DatabaseDescriptor.getRequestSchedulerId().equals(RequestSchedulerId.keyspace);
// Current user for the session
private final ThreadLocal<AuthenticatedUser> user = new ThreadLocal<AuthenticatedUser>()
@ -80,11 +77,16 @@ public class ClientState
updateKeyspaceAccess();
}
public String getSchedulingId()
public String getSchedulingValue()
{
if (SCHEDULE_ON_KEYSPACE)
return keyspace.get();
return "default";
String schedulingValue = "default";
switch(DatabaseDescriptor.getRequestSchedulerId())
{
case keyspace:
schedulingValue = keyspace.get();
break;
}
return schedulingValue;
}
/**

2
src/java/org/apache/cassandra/thrift/CassandraServer.java
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@ -615,7 +615,7 @@ public class CassandraServer implements Cassandra.Iface
*/
private void schedule()
{
requestScheduler.queue(Thread.currentThread(), clientState.getSchedulingId());
requestScheduler.queue(Thread.currentThread(), clientState.getSchedulingValue());
}
/**