public class WeightedLeastConnectionsRouter extends RouterImpl
Statistics for the following records are enabled: Peer,AppGenRequestPerSecond,NetGenRequestPerSecond
In the client configuration, please use the following settings:
......
RouterImpl.AnswerEntry, RouterImpl.RedirectEntryALL_APPLICATION, ALL_HOST, ALL_REALM, ALL_SESSION, ALL_USER, concurrentFactory, container, DONT_CACHE, isStopped, metaData, REALM_AND_APPLICATION, realmTable, REDIRECT_TABLE_SIZE, redirectTable, redirectTableLock, REQUEST_TABLE_CLEAR_SIZE, REQUEST_TABLE_SIZE, requestEntryMap, requestEntryTableLock| Modifier | Constructor and Description |
|---|---|
|
WeightedLeastConnectionsRouter(IContainer container,
IConcurrentFactory concurrentFactory,
IRealmTable realmTable,
Configuration config,
MetaData aMetaData) |
protected |
WeightedLeastConnectionsRouter(IRealmTable table,
Configuration config) |
| Modifier and Type | Method and Description |
|---|---|
protected long |
getNumConnections(IPeer peer)
Since num connections is not available, determine throughput by reading statistics
and assume the load of the peer
|
protected long |
getRecord(String record,
IStatistic stats)
Return statistics record value from given
IStatistic |
IPeer |
selectPeer(List<IPeer> availablePeers)
Return peer with least connections
|
destroy, garbageCollectRequestRouteInfo, getPeer, getPeerPredProcessing, getRealmTable, getRequestRouteInfo, loadConfiguration, processRedirectAnswer, registerRequestRouteInfo, start, stop, updateRouteprotected WeightedLeastConnectionsRouter(IRealmTable table, Configuration config)
public WeightedLeastConnectionsRouter(IContainer container, IConcurrentFactory concurrentFactory, IRealmTable realmTable, Configuration config, MetaData aMetaData)
public IPeer selectPeer(List<IPeer> availablePeers)
The weighted least-connection scheduling is a superset of the least-connection scheduling, in which you can assign a performance weight to each real server. The servers with a higher weight value will receive a larger percentage of active connections at any one time. The default server weight is one, and the IPVS Administrator or monitoring program can assign any weight to real server. In the weighted least-connections scheduling, new network connection is assigned to a server which has the least ratio of the current active connection number to its weight.
Supposing there is a server set S = {S0, S1, ..., Sn-1}, W(Si) is the weight of server Si; C(Si) is the current connection number of server Si; CSUM = ΣC(Si) (i=0, 1, .. , n-1) is the sum of current connection numbers;
The new connection is assigned to the server j, in which (C(Sm) / CSUM)/ W(Sm) = min { (C(Si) / CSUM) / W(Si)} (i=0, 1, . , n-1), where W(Si) isn't zero Since the CSUM is a constant in this lookup, there is no need to divide by CSUM, the condition can be optimized as C(Sm) / W(Sm) = min { C(Si) / W(Si)} (i=0, 1, . , n-1), where W(Si) isn't zero
Since division operation eats much more CPU cycles than multiply operation, and Linux does not allow float mode inside the kernel, the condition C(Sm)/W(Sm) > C(Si)/W(Si) can be optimized as C(Sm)*W(Si) > C(Si)*W(Sm). The scheduling should guarantee that a server will not be scheduled when its weight is zero. Therefore, the pseudo code of weighted least-connection scheduling algorithm is
for (m = 0; m < n; m++) {
if (W(Sm) > 0) {
for (i = m+1; i < n; i++) {
if (C(Sm)*W(Si) > C(Si)*W(Sm))
m = i;
}
return Sm;
}
}
return NULL;
The weighted least-connection scheduling algorithm requires additional division than the least-connection scheduling. In a hope to minimize the overhead of scheduling when servers have the same processing capacity, both the least-connection scheduling and the weighted least-connection scheduling algorithms are implemented.
selectPeer in class RouterImplavailablePeers - list of peers that are in OKAY stateprotected long getNumConnections(IPeer peer)
peer - protected long getRecord(String record, IStatistic stats)
IStatisticrecord - key to retrievestats - statistic objectCopyright © 2017. All Rights Reserved.