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CLOUDSTACK-4636: In a scaled up setup all Vm's in a cluster were stopped and/or started after management server restart 

Issue happens as there are more than one thread processing connect for a host simultaneously. The VM full sync. is not designed to work in this scenario and as a result user VMs may get stopped incorrectly.
Direct agent scan task runs at regular intervals (direct.agent.scan.interval defaulted to 90 secs) and identifies hosts that needs to be processed for connect. In a normal scenario hosts mostly get connected within that interval and there are no issues. But if due to some reason the connect process takes more time and is not completed by the time next agent scan runs. In this case, based on the db. state same hosts may get picked up again. And then there will be situations where more than one thread is processing connect for the same host.
The fix is to check if there is a thread already processing connect for a host and in this case all subsequent threads for that host will simply bail out. Also there may be a scenario where one thread already completed processing connect but another thread already got scheduled before that and will again repeat the same. This is also prevented by putting appropriate checks.
This commit is contained in:
Koushik Das 2013-09-10 11:54:32 +05:30
parent e607998afa
commit ab60e9eae9
2 changed files with 21 additions and 4 deletions
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5
server/src/com/cloud/agent/manager/AgentManagerImpl.java
View File

@ -1376,7 +1376,10 @@ public class AgentManagerImpl extends ManagerBase implements AgentManager, Handl
public boolean tapLoadingAgents(Long hostId, TapAgentsAction action) {
synchronized (_loadingAgents) {
if (action == TapAgentsAction.Add) {
_loadingAgents.add(hostId);
if (_loadingAgents.contains(hostId))
return false;
else
_loadingAgents.add(hostId);
} else if (action == TapAgentsAction.Del) {
_loadingAgents.remove(hostId);
} else if (action == TapAgentsAction.Contains) {

20
server/src/com/cloud/resource/ResourceManagerImpl.java
View File

@ -1920,9 +1920,23 @@ public class ResourceManagerImpl extends ManagerBase implements ResourceManager,
@Override
public Host createHostAndAgent(Long hostId, ServerResource resource, Map<String, String> details, boolean old, List<String> hostTags,
boolean forRebalance) {
_agentMgr.tapLoadingAgents(hostId, TapAgentsAction.Add);
Host host = createHostAndAgent(resource, details, old, hostTags, forRebalance);
_agentMgr.tapLoadingAgents(hostId, TapAgentsAction.Del);
Host host = null;
if (_agentMgr.tapLoadingAgents(hostId, TapAgentsAction.Add)) {
try {
AgentAttache agentattache = _agentMgr.findAttache(hostId);
if (agentattache == null) {
s_logger.debug("Creating agent for host " + hostId);
host = createHostAndAgent(resource, details, old, hostTags, forRebalance);
s_logger.debug("Completed creating agent for host " + hostId);
} else {
s_logger.debug("Agent already created in another thread for host " + hostId + ", ignore this");
}
} finally {
_agentMgr.tapLoadingAgents(hostId, TapAgentsAction.Del);
}
} else {
s_logger.debug("Agent creation already getting processed in another thread for host " + hostId + ", ignore this");
}
return host;
}