Christian Mamen created AMQ-5086:
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Summary: vm transport create=false&waitForStart race condition
Key: AMQ-5086
URL: https://issues.apache.org/jira/browse/AMQ-5086
Project: ActiveMQ
Issue Type: Bug
Components: Broker
Affects Versions: 5.7.0
Reporter: Christian Mamen
Experience this bug on 5.7.0, I think this is the same on the trunk
using vm transport for a client to connect to an embedded broker, in a
multithreaded application, I'm experiencing a an error (sometimes) which
appears to be a race condition at startup.
Im using create=false and waitForStart to create a connectionFactory for a
client connection
vm://ApplicationName?create=false&waitForStart=120000
The broker service is started in a seperate thread
the client connection is started first. but surprisingly it tries start the
brokers transport connector. An apparent glitch follows when the broker service
stops and re-start the transport.
{noformat}
2014-03-05 11:07:57,626 [ClientConnection_thread] INFO
org.apache.activemq.broker.TransportConnector - Connector vm://ApplicationName
Started
[...]
2014-03-05 11:08:07,009 [Main_thread] INFO
org.apache.activemq.broker.TransportConnector - Connector vm://ApplicationName
Stopped
2014-03-05 11:08:07,011 [Main_thread] INFO
org.apache.activemq.broker.TransportConnector - Connector vm://ApplicationName
Started
{noformat}
I look into the activemq source and saw this:
BrokerService.class
{code}
public void start() throws Exception {
[...]
// in jvm master slave, lets not publish over existing broker till we get
the lock
final BrokerRegistry brokerRegistry = BrokerRegistry.getInstance();
if (brokerRegistry.lookup(getBrokerName()) == null) {
brokerRegistry.bind(getBrokerName(), BrokerService.this);
}
startPersistenceAdapter(startAsync);
startBroker(startAsync);
brokerRegistry.bind(getBrokerName(), BrokerService.this);
{code}
VMTransportFactory.class
{code}
private BrokerService lookupBroker(final BrokerRegistry registry, final
String brokerName, int waitForStart) {
BrokerService broker = null;
synchronized(registry.getRegistryMutext()) {
broker = registry.lookup(brokerName);
if (broker == null && waitForStart > 0) {
final long expiry = System.currentTimeMillis() + waitForStart;
while (broker == null && expiry > System.currentTimeMillis()) {
long timeout = Math.max(0, expiry -
System.currentTimeMillis());
try {
LOG.debug("waiting for broker named: " + brokerName + "
to start");
registry.getRegistryMutext().wait(timeout);
} catch (InterruptedException ignored) {
}
broker = registry.lookup(brokerName);
}
}
}
return broker;
}
{code}
It appears that create=false and waitForStart only waits for the broker to be
added to the BrokerRegistry. However when the brokerService is starts, it seems
that the broker is added to the registry before it is started.
I believe some synchronization is missing make the VMTransportFactory wait for
the broker not only to be added to the registry, but also fully started.
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