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Removed unnecessary loop of servers. Now we loop over all the servers, if running server is found and candidate is not set we set that server as candidate. If candidate is set and we find any that have fewer connections than our candidate server. If a server has less connections than the current candidate we mark this as the new candidate to connect to. If a server has the same number of connections currently as the candidate and has had less connections over time than the candidate it will also become the new candidate. This has the effect of spreading the connections over different servers during periods of very low load.

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This commit is contained in:
Jan Lindström 2013-08-13 11:55:34 +03:00
parent 8a31819d03
commit c1c8bf9fc5
1 changed files with 41 additions and 42 deletions
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83
server/modules/routing/readconnroute.c
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@ -246,8 +246,7 @@ CLIENT_SESSION *client;
BACKEND *candidate = NULL;
int i;
if ((client = (CLIENT_SESSION *)malloc(sizeof(CLIENT_SESSION))) == NULL)
{
if ((client = (CLIENT_SESSION *)malloc(sizeof(CLIENT_SESSION))) == NULL) {
return NULL;
}
/*
@ -256,23 +255,6 @@ int i;
* connection router.
*/
/* First find a running server to set as our initial candidate server */
for (i = 0; inst->servers[i]; i++)
{
if (inst->servers[i] && SERVER_IS_RUNNING(inst->servers[i]->server)
&& (inst->servers[i]->server->status & inst->bitmask) == inst->bitvalue)
{
candidate = inst->servers[i];
skygw_log_write(
LOGFILE_TRACE,
"Selected server in port %d to as candidate. "
"Connections : %d\n",
candidate->server->port,
candidate->count);
break;
}
}
/*
* Loop over all the servers and find any that have fewer connections than our
* candidate server.
@ -285,33 +267,50 @@ int i;
* become the new candidate. This has the effect of spreading the connections
* over different servers during periods of very low load.
*/
for (i = 1; inst->servers[i]; i++)
{
skygw_log_write(
LOGFILE_TRACE,
"Examine server in port %d with %d connections. Status is %d, "
"inst->bitvalue is %d",
inst->servers[i]->server->port,
inst->servers[i]->count,
inst->servers[i]->server->status,
inst->bitmask);
for (i = 0; inst->servers[i]; i++) {
if(inst->servers[i]) {
skygw_log_write(
LOGFILE_TRACE,
"Examine server in port %d with %d connections. Status is %d, "
"inst->bitvalue is %d",
inst->servers[i]->server->port,
inst->servers[i]->count,
inst->servers[i]->server->status,
inst->bitmask);
}
if (inst->servers[i] && SERVER_IS_RUNNING(inst->servers[i]->server)
&& (inst->servers[i]->server->status & inst->bitmask) == inst->bitvalue)
{
if (inst->servers[i]->count < candidate->count)
{
candidate = inst->servers[i];
if (inst->servers[i] && SERVER_IS_RUNNING(inst->servers[i]->server)
&& (inst->servers[i]->server->status & inst->bitmask) == inst->bitvalue) {
/* If no candidate set, set first running server as
our initial candidate server */
if (candidate == NULL) {
candidate = inst->servers[i];
} else if (inst->servers[i]->server->stats.n_connections
< candidate->server->stats.n_connections) {
/* This running server has fewer
connections, set it as a new candidate */
candidate = inst->servers[i];
} else if (inst->servers[i]->server->stats.n_connections
== candidate->server->stats.n_connections &&
inst->servers[i]->count < candidate->count) {
/* This running server has the same number
of connections currently as the candidate
but has had fewer connections over time
than candidate, set this server to candidate*/
candidate = inst->servers[i];
}
else if (inst->servers[i]->count == candidate->count &&
inst->servers[i]->server->stats.n_connections
< candidate->server->stats.n_connections)
{
candidate = inst->servers[i];
}
}
}
if (candidate) {
skygw_log_write(
LOGFILE_TRACE,
"Selected server in port %d to as candidate. "
"Connections : %d\n",
candidate->server->port,
candidate->count);
}
/* no candidate server here, clean and return NULL */
if (!candidate) {
free(client);