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https://issues.apache.org/jira/browse/TINKERPOP-1127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15133908#comment-15133908
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Ramzi Oueslati commented on TINKERPOP-1127:
-------------------------------------------
Hi
I definitely agree with the _open_ variable not being decremented when the
connections are destroyed.
Another point : in addConnectionIfUnderMaximum, if opened < maxPoolSize then
_open_ is incremented and a new Connection is added to the pool. What if "new
Connection(...)" fails ? Well _open_ gets incremented anyway.
That's why I would also add this :
{code}
@@ -300,6 +303,7 @@ final class ConnectionPool {
try {
connections.add(new Connection(host.getHostUri(), this,
settings().maxInProcessPerConnection));
} catch (ConnectionException ce) {
+ open.decrementAndGet();
logger.debug("Connections were under max, but there was an error
creating the connection.", ce);
considerUnavailable();
return false;
{code}
> client fails to reconnect to restarted server
> ---------------------------------------------
>
> Key: TINKERPOP-1127
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1127
> Project: TinkerPop
> Issue Type: Bug
> Components: driver
> Affects Versions: 3.1.0-incubating
> Reporter: Kieran Sherlock
> Assignee: stephen mallette
> Fix For: 3.1.2-incubating
>
>
> If a gremlin-server is restarted, the client will never reconnect to it.
> Start server1
> Start server2
> Start client such as
> {code}
> GryoMapper kryo =
> GryoMapper.build().addRegistry(TitanIoRegistry.INSTANCE).create();
> MessageSerializer serializer = new GryoMessageSerializerV1d0(kryo);
> Cluster titanCluster = Cluster.build()
> .addContactPoints("54.X.X.X,54.Y.Y.Y".split(","))
> .port(8182)
> .minConnectionPoolSize(5)
> .maxConnectionPoolSize(10)
> .reconnectIntialDelay(1000)
> .reconnectInterval(30000)
> .serializer(serializer)
> .create();
> Client client = titanCluster.connect();
> client.init();
> System.out.println("initialized");
> for (int i = 0; i < 200; i++) {
> try {
> long id = System.currentTimeMillis();
> ResultSet results = client.submit("graph.addVertex('a','" +
> id + "')");
> results.one();
> results = client.submit("g.V().has('a','" + id + "')");
> System.out.println(results.one());
> } catch (Exception e) {
> e.printStackTrace();
> }
> try {
> TimeUnit.SECONDS.sleep(3);
> } catch (InterruptedException e) {
> e.printStackTrace();
> }
> }
> System.out.println("done");
> client.close();
> System.exit(0);
> }
>
{code}
> After client has performed a couple of query cycles
> Restart server1
> Wait 60 seconds so the reconnect should occur
> stop server2
> Notice that there are no more successful queries, the client has never
> reconnected to server1
> start server2
> Notice that still there are no more successful queries
> The method ConnectionPool.addConnectionIfUnderMaximum is always returning
> false because opened >= maxPoolSize. In this particular case opened = 10. I
> believe that open is trying to track the size of the List of connections but
> is getting out of sync. The following diff addresses this problem for this
> particular case
> {code:diff}
> diff --git
> a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
>
> b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
> index 96c151c..81ce81d 100644
> ---
> a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
> +++
> b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
> @@ -326,6 +326,7 @@ final class ConnectionPool {
> private void definitelyDestroyConnection(final Connection connection) {
> bin.add(connection);
> connections.remove(connection);
> + open.decrementAndGet();
> if (connection.borrowed.get() == 0 && bin.remove(connection))
> connection.closeAsync();
> @@ -388,6 +389,8 @@ final class ConnectionPool {
> // if the host is unavailable then we should release the connections
> connections.forEach(this::definitelyDestroyConnection);
> + // there are no connections open
> + open.set(0);
> // let the load-balancer know that the host is acting poorly
> this.cluster.loadBalancingStrategy().onUnavailable(host);
> @@ -413,6 +416,7 @@ final class ConnectionPool {
> this.cluster.loadBalancingStrategy().onAvailable(host);
> return true;
> } catch (Exception ex) {
> + logger.debug("Failed reconnect attempt on {}", host);
> if (connection != null) definitelyDestroyConnection(connection);
> return false;
> }
> {code}
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